Analysis of the high-resolution 5-μm spectra of the ν4(E) and 2ν2(A1) bands of 12CD3F

The infrared spectrum of the ν₄(E) and 2ν₂(A₁) bands of ¹²CD₃F have been recorded and deconvolved to ∼0.005 cm⁻¹ resolution. More than 1890 transitions have been assigned to one of the 37 subbands (−18≤KΔK≤+18) comprising the spectrum of the ν₄ band with a maximum assigned J value of 41. The weak 2ν₂(A₁) band has never been reported in the infrared prior to this work. A total of 358 transitions in K ≤ 8 subbands have been assigned to the 2ν₂ band. The two bands are members of the 24 interacting state complex of ¹²CD₃F spectra in the 5-μm region. The ν₄ and 2ν₂ spectra are highly perturbed, exhibiting local and global resonances. Effective parameters of the two bands were obtained by fitting the data in a restricted manner leaving out the obviously perturbed transitions. The effective parameters, the identification of the different resonances affecting the bands, and estimates of some of the coupling constants are reported.     

Diode laser measurements of line strengths and widths in the 4.5-μm bands of N2O

We have made line-strength measurements in the N₂O ν₃-fundamental region using a tunable diode-laser spectrometer. From these measurements and the Herman-Wallis factor determined by Boissy et al., we find the ν₃-fundamental band strength to be S_v = 1203 ± 22 cm⁻² atm⁻¹ at 297 K. Line-broadening parameters for two ν₃-fundamental lines were determined using nitrogen (N₂) as the broadening gas. Measured strengths and N₂ line-broadening parameters for several (ν¹₂ + ν₃ − ν¹₂) hot-band lines are also presented.     

Laser Stark spectroscopy in the 9.4-μm region: The ν2 and ν5 bands of methyl chloride-d3

About two hundred Stark resonances of the ν₂ and ν₅ vibration-rotation bands of CD₃³⁵Cl, using a 9.4 μm CO₂ laser as a source, have been measured. By combining these data with the zero-field microwave spectra the following molecular constants have been determined (with the standard deviations in parentheses):

     

4.

Laser Stark and diode laser spectroscopy of the 10-μm bands of CH2NH: Determination of the dipole moment orientation     

《Journal of Molecular Spectroscopy》1987,124(1):99-117

The complexities apparent in the laser Stark spectra obtained from the 10-μm band system of CH₂NH are shown to be due to the interplay of the a and b components of the Coriolis and Stark effect coupling. As a result it has been possible to determine the relative orientations of the a and b components of the permanent electric dipole moment. This is analogous to the determination of the relative signs of the dipole moment derivatives from the analysis of the intensity perturbations produced by Coriolis interaction.A detailed comparison has also been made of the uses of laser Stark, diode laser, and Fourier transform spectroscopy for studying heavily perturbed molecular spectra.     

5.

Passive polarization rotator based on silica photonic crystal fiber for 1.31-μm and 1.55-μm bands via adjusting the fiber length          下载免费PDF全文

陈雷  张伟刚  王丽  白志勇  张珊珊  王标  严铁毅  Jonathan Sieg 《中国物理 B》2014,(10):230-234

A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber （PR-PCF） possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance - 100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.     

6.

Analysis of the laser performance of Tm³⁺: ZBLAN glass at 1.47μm wavelength          下载免费PDF全文

黄莉蕾  曹国熹  张伦  罗宏雷 《中国物理》2004,13(10):1728-1732

A formula for the threshold energy of a four-level-system laser in Tm^{3+} doped fluoride glass is derived. The formula contains the parameters of the interaction between the ions and the up-conversion rate of the pump-light. It is discussed that the Tb^{3+} ions and the up-conversion pump-light have an influence on the laser performance of Tm^{3+} ions around 1.47μm wavelength. We draw the following two conclusions. (1) The laser threshold descends obviously due to the doping of Tb^{3+} ions, but the descending gradually flattens out with the increase of the content of Tb^{3+} ions. Its suitable content is (1－2)×10^{20}cm^{-3}. (2) When pump-lights both from the up-conversion and from the ground state excite simultaneously the single-doped Tm^{3+} ions, the threshold energy can reduce and the output energy can increase. In this paper, the energy conversion efficiency from the up-conversion pump-light to the output energy of laser is estimated.     

7.

The first high-resolution analysis of the 10-μm absorption of thioformaldehyde     

J.-M. Flaud  A. Perrin  H. Beckers 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(6):995-1003

The 10 μm region of thioformaldehyde (H₂CS) has been recorded at high resolution (0.005 cm⁻¹) using a Fourier transform spectrometer. H₂CS was produced by low-pressure pyrolysis of a gas flow of C₃H₅SCH₃ in Ar at 560 °C or CH₃SCl at 1150 °C, which was introduced into a multipass White cell with an optical path length of 32 m. Forty scans were recorded for the range 750-1400 cm⁻¹ at a total pressure of 0.15 mbar. A thorough analysis of the three lowest wavenumber fundamental bands, ν₃, ν₄ and ν₆, which fall in this region, has been carried out using a Hamiltonian model, which takes explicitly into account the numerous resonances affecting the ro-vibrational energy levels; especially the massive A-type Coriolis resonance between the out-of-plane wagging mode, ν₄, and the in-plane rocking mode, ν₆. These two modes are only separated by 0.83 cm⁻¹, and they are thoroughly mixed. From the fittings, the following band centers were derived: ν_o (ν₄)=990.18213(40) cm⁻¹, ν_o (ν₆)=991.02021(50) cm⁻¹ and ν_o (ν₃)=1059.20476 (30) cm⁻¹ where the uncertainties are one standard deviation. In addition, a number of relative line intensities were measured permitting the determination of relative values of the first-order transition moments and therefore relative band intensities for all three bands. Finally, a comprehensive list of line wavenumbers and relative intensities has been generated.     

8.

Frequency measurements in the 9μm spectrum of CF3Br     

《Infrared physics》1990,30(3):279-284

Carbon dioxide laser saturation spectra of CF₃ Br have been explored with a view to hyperfine spectroscopy and references for frequency standards in the 9μm band of the carbon dioxide laser. Spectra have been obtained using the laser transitions 9R(16)-9R(30). and show many saturation features in each case. Several of the stronger features have been referenced directly to CO₂ frequencies with an estimated accuracy of 25 kHz. Spacings between the hyperfine components are also reported. This work represents some of the first data relevant to 9μm locking to molecular absorptions.     

9.

Absolute line intensities measurements and calculations for the 5.7 and 3.6 μm bands of formaldehyde     

A. Perrin  D. Jacquemart  F. Kwabia Tchana  N. Lacome 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(9-10):700-716

The goal of this study is to achieve absolute line intensities for the strong 5.7 and 3.6 μm bands of formaldehyde and to generate, for both spectral regions, an accurate list of line positions and intensities. Both bands are now used for the infrared measurements of this molecule in the atmosphere. However, in the common access spectroscopic databases there exists, up to now, no line parameters for the 5.7 μm region, while, at 3.6 μm, the quality of the line parameters is quite unsatisfactory. High-resolution Fourier transform spectra were recorded for the whole 1600–3200 cm^?1 spectral range and for different path-length-pressure products conditions. Using these spectra, a large set of H₂CO individual line intensities was measured simultaneously in both the 5.7 and 3.6 μm spectral regions. From this set of experimental line strength which involve, at 5.7 μm the ν₂ band and, at 3.6 μm, the ν₁ and ν₅ bands together with nine dark bands, it has been possible to derive a consistent set of line intensity parameters for both the 5.7 and 3.6 μm spectral regions. These parameters were used to generate a line list in both regions. For this task, we used the line positions generated in [Margulés L, Perrin A, Janeckovà R, Bailleux S, Endres CP, Giesen TF, et al. Can J Phys, accepted] and [Perrin A, Valentin A, Daumont L, J Mol Struct 2006;780–782:28–42] for the 5.7 and 3.6 μm, respectively. The calculated band intensities derived for the 5.7 and 3.6 μm bands are in excellent agreement with the values achieved recently by medium resolution band intensity measurements. It has to be mentioned that intensities in the 3.6 μm achieved in this work are on the average about 28% stronger than those quoted in the HITRAN or GEISA databases. Finally, at 3.6 μm the quality of the intensities was significantly improved even on the relative scale, as compared to our previous study performed in 2006.     

10.

Interaction of 3μm radiation with matter     

J. Frauchiger  W. Lüthy 《Optical and Quantum Electronics》1987,19(4):231-236

Drilling of small holes into media containing O-H or C-H bonds with a 2.92m YAIO₃-Er laser is studied. In materials containing O-H bonds strong absorption allows small volumina to be heated with only marginal heat diffusion. Drilling with nearly diffraction-limited lateral resolution is achieved.     

11.

Analysis of the Isotopic Composition of Exhaled Air by the Diode Laser Spectroscopy Method in the 2-μm Region for Diagnosis of Helicobacter pylori-Associated Diseases     

Ivashkin  V. T.  Kasoev  S. G.  Stepanov  E. V. 《Optics and Spectroscopy》2019,126(6):710-720

Optics and Spectroscopy - To diagnose digestive diseases associated with Helicobacter pylori infection, we applied laser spectroscopic analysis of the 13СО2/12СО2 isotope...     

12.

Assessment of the 200-μm Atmospheric Window for Ground-Based Astronomy     

H. M. Araújo  R. J. Walker  S. A. Rinehart  M. J. Griffin  P. A. R. Ade 《International Journal of Infrared and Millimeter Waves》2001,22(7):965-982

Submillimetre astronomy with ground-based instruments is currently restricted to spectral windows below 1 THz where the atmosphere is not very opaque. Recently, it was shown that supra-terahertz windows also unfold under very good atmospheric conditions, and could be explored for this effect. In particular, the 200 m window (1.5 THz) can transmit up to 30% on exceptionally dry weather at high-altitude sites. This study was conducted in parallel with the designs of THUMPER, a Two Hundred Micron Photometer for the James Clerk Maxwell Telescope, in Hawaii. Here we consider the weather conditions required and how often they arise, both by modelling the spectral transmittance of the atmosphere at 200 m and by analysing opacity data at 225 GHz. Implications for submillimetre astronomy are discussed. This study could benefit the ongoing analysis of other observation sites.     

13.

Experimental investigation of the 2.1-μm single-mode Tm-Ho:KYF laser     

G.?GalzeranoEmail author  E.?Sani  A.?Toncelli  S.?Taccheo  M.?Tonelli  P.?Laporta 《Applied physics. B, Lasers and optics》2004,78(6):733-736

We report on the development and comprehensive characterization of a room-temperature single-mode 2-m Tm-Ho:KYF laser. A maximum CW output power of 70 mW at the central wavelength of 2.078 m has been obtained. Using a 5-mm long intracavity birefringent filter the single-mode emission wavelength can be tuned over a range of 40 nm. Both frequency and relative intensity noise have been investigated showing a 1-ms emission linewidth of 600 kHz and an intensity noise spectrum that is quantum-noise limited for Fourier frequencies higher than 1 MHz. PACS 42.55Xi; 42.55Rz; 42.60Pk; 42.70Hj; 42.60Lh     

14.

Analysis of the stimulated Raman spectrum of the ν16ν2 + ν18 Fermi dyad of benzene     

《Journal of Molecular Spectroscopy》1987,125(2):393-412

Ionization-detected stimulated Raman spectroscopy was used to obtain high-resolution recordings of the two perpendicular bands of the benzene molecule centered at 1591.327 and 1609.518 cm⁻¹. The effective resolution was further enhanced by deconvolving the spectrum to a linewidth 0.003 to 0.004 cm⁻¹. Fine-tuning of the ionizing radiation made it possible to record the transitions belonging to each band separately, thus greatly simplifying the spectrum in the region of overlap. The strong ^sS and ^oO branches were, for the most part, completely resolved as were many lines in the weaker ^oP and ^sR branches and even in the central ^oQ and ^sQ branches. The observed bands belong to the E_2g fundamental ν₁₆ in nearly exact Fermi resonance with the combination ν₂ + ν₁₈. A detailed rovibrational analysis of the spectrum is reported. A perturbation detected in the ^sS_k branches of the lower-frequency band for K = 19 to 23 was identified as a quintic anharmonic resonance with the third overtone, 4ν₂₀, of the lowest lying fundamental ν₂₀, which is infrared- and Raman-inactive (species E_2u). Deperturbed spectroscopic constants for the interacting states are reported which reproduce the observed line positions with a standard deviation of 0.0013 cm⁻¹. The unperturbed origins of the ν₁₆ and ν₂ + ν₁₈ states are only 1.106 cm⁻¹ apart. The fundamental ν₁₆ was identified with the higher-frequency state with origin at 1600.976 cm⁻¹.     

15.

High resolution analysis of the ethylene-1-C spectrum in the 8.4-14.3-μm region     

J.-M. Flaud  Robert Sams 《Journal of Molecular Spectroscopy》2010,259(1):39-45

Fourier transform spectra of mono-¹³C ethylene have been recorded in the 8.4-14.3-μm spectral region (700-1190 cm⁻¹) using a Bruker 120 HR interferometer at a resolution of 0.0017 cm⁻¹ allowing the extensive study of the set of resonating states {10¹, 8¹, 7¹, 4¹, 6¹}. Due to the high resolution available as well as the extended spectral range involved in this study, a much larger set of line assignments are now available. The present analysis has lead to the determination of more accurate spectroscopic constants, including interaction constants, than were obtained in earlier studies. In particular, the following band centers were derived: ν₀(ν₁₀) = 825.40602(30) cm⁻¹, ν₀(ν₈) = 932.19572(15) cm⁻¹, ν₀(ν₇) = 937.44452(10) cm⁻¹, ν₀(ν₄) = 1025.6976(14) cm⁻¹. Finally a synthetic spectrum was generated leading to the assignment of a number of ¹³C¹²CH₄ lines observed in an earlier heterodyne spectroscopic study.     

16.

Dual-Frequency Generation in Quantum Cascade Lasers of the 8-μm Spectral Range     

V. V. Dudelev  S. N. Losev  V. Yu. Mylnikov  A. V. Babichev  E. A. Kognovitskaya  S. O. Slipchenko  A. V. Lutetskii  N. A. Pikhtin  A. G. Gladyshev  L. Ya. Karachinskii  I. I. Novikov  A. Yu. Egorov  V. I. Kuchinskii  G. S. Sokolovskii 《Optics and Spectroscopy》2018,125(3):402-404

Results of an investigation of quantum cascade lasers of the 8-μm spectral range generating dual-frequency radiation at room temperature are presented. The dependences of radiation intensity for two lines of laser generation obtained as a result of investigation of the generation spectra revealed the presence of saturation and decay of the long-wavelength line of generation and linear growth of the intensity of the short-wavelength one. Based on analysis of the obtained data, a mechanism of the dual-frequency generation in the studied QCL samples is proposed Generation.     

17.

Isotopic shift of the ground state of neon from the experimental results concerning the absorption of 0.63-μm laser radiation     

E. G. Saprykin 《Optics and Spectroscopy》2017,122(4):549-560

Isotopic shifts of the 3s[3/2] ₁ ⁰ –2р ⁶(¹ S ₀) and 3s'–2р ⁶(¹ S ₀) transitions, equal, respectively, to 417 ± 20 and–98 ± 20 MHz, have been measured using the 0.63-μm radiation of a helium–neon laser and opto-magnetic resonances induced by the interference of the reactive components of fields in overlapping areas of the emissions of isotopic atoms. Combining these results with the absolute specific mass shift of the 3p[5/2]₂ level (–647 MHz), the isotopic mass shift of the ground state of neon equal to 3223 ± 30 MHz, and its specific mass shift equal to–9782 ± 30 MHz have been determined.     

18.

Spectral measurements of high-temperature isotopic carbon dioxide in the 4.5- and 2.8-μm regions     

《Journal of Molecular Spectroscopy》1986,116(2):351-363

High-resolution measurements have been made using the AFGL 2-m path difference Fourier transform spectrometer on isotopically enriched samples of carbon dioxide. Two regions were investigated: 2140–2320 and 3470–3770 cm⁻¹. The samples were observed in absorption at temperatures up to 800 K. Observed line positions to high rotational levels were obtained for 15 parallel bands with Δv₃ = 1 for the isotopic variants ¹³C¹⁶O₂, ¹³C¹⁶O¹⁸O, and ¹³C¹⁶O¹⁷O in the 4.5-μm region and for 23 bands of the type Δv₁ = 1, Δv₃ = 1 for the species ¹²C¹⁶O₂, ¹²C¹⁶O¹⁸O, and ¹²C¹⁸O₂ in the 2.8-μm region.     

19.

A high-resolution study of the ν3 and 2ν80 bands of propyne     

《Journal of Molecular Spectroscopy》1987,121(1):150-166

The ν₃ and 2ν₈⁰ parallel bands of propyne (methyl acetylene) at 2137.88 and 2066.33 cm⁻¹ have been studied at 0.006 cm⁻¹ resolution. Their Fermi resonance and interaction with the ν₈ + 2ν₉, ν₇ + ν₉, and ν₈ + ν₉ + ν₁₀ levels have been investigated. Molecular constants were determined from the assignment of 1150 lines. However, the rms error of 0.0028 cm⁻¹ showed the presence of additional perturbations which cannot be uniquely identified.     

20.

Analysis of the hot bands in the 2ν₉ band region of propyne-d₃     

Geetha Rajappan 《Journal of Molecular Spectroscopy》2004,224(2):107-113

The rovibrational spectrum of 2ν₉ band of CD₃CCH is overlapped by two prominent hot bands identified as (2ν₉⁰+ν₁₀^±1)(E)←ν₁₀^±1(E) and 3ν₉^±1(E)←ν₉^±1(E), where ν₁₀ and ν₉ are the degenerate CCC and CCH bending fundamental vibrations, respectively. Assignment of lines to the transitions of these hot bands were carried out with the help of the high-resolution spectra recorded at ∼195 K and at room temperature. Molecular parameters for these hot bands have been obtained from the rotational analysis of the partially resolved K-structure lines. Only Q-head of the third hot band , originating from the lower 2ν₁₀ state could be identified.     

		$\text{ν}{}_2$		$\text{ν}{}_5$
$\text{ν}{}_0$		1 028.67275 (15)		1 059.96970 (11)		(cm?1)
$\text{A}$		78 765.20 (89)		78 030.21 (109)		(MHz)
$\text{B}{}^1$		10 805.29 (26)		10 860.10 (13)		(MHz)
$\text{Aζ}{}_5$				?25 080.77 (99)		(MHz)
$\text{D}$			8 756.0 (43)			(MHz)
μ		1.90741 (33)		1.90607 (36)		(D)
μ(ground state)			1.90597 (33)			(D)

Laser Stark and diode laser spectroscopy of the 10-μm bands of CH2NH: Determination of the dipole moment orientation

The complexities apparent in the laser Stark spectra obtained from the 10-μm band system of CH₂NH are shown to be due to the interplay of the a and b components of the Coriolis and Stark effect coupling. As a result it has been possible to determine the relative orientations of the a and b components of the permanent electric dipole moment. This is analogous to the determination of the relative signs of the dipole moment derivatives from the analysis of the intensity perturbations produced by Coriolis interaction.A detailed comparison has also been made of the uses of laser Stark, diode laser, and Fourier transform spectroscopy for studying heavily perturbed molecular spectra.     

Passive polarization rotator based on silica photonic crystal fiber for 1.31-μm and 1.55-μm bands via adjusting the fiber length

A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber （PR-PCF） possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance - 100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.     

Analysis of the laser performance of Tm3+: ZBLAN glass at 1.47μm wavelength

A formula for the threshold energy of a four-level-system laser in Tm^{3+} doped fluoride glass is derived. The formula contains the parameters of the interaction between the ions and the up-conversion rate of the pump-light. It is discussed that the Tb^{3+} ions and the up-conversion pump-light have an influence on the laser performance of Tm^{3+} ions around 1.47μm wavelength. We draw the following two conclusions. (1) The laser threshold descends obviously due to the doping of Tb^{3+} ions, but the descending gradually flattens out with the increase of the content of Tb^{3+} ions. Its suitable content is (1－2)×10^{20}cm^{-3}. (2) When pump-lights both from the up-conversion and from the ground state excite simultaneously the single-doped Tm^{3+} ions, the threshold energy can reduce and the output energy can increase. In this paper, the energy conversion efficiency from the up-conversion pump-light to the output energy of laser is estimated.     

The first high-resolution analysis of the 10-μm absorption of thioformaldehyde

The 10 μm region of thioformaldehyde (H₂CS) has been recorded at high resolution (0.005 cm⁻¹) using a Fourier transform spectrometer. H₂CS was produced by low-pressure pyrolysis of a gas flow of C₃H₅SCH₃ in Ar at 560 °C or CH₃SCl at 1150 °C, which was introduced into a multipass White cell with an optical path length of 32 m. Forty scans were recorded for the range 750-1400 cm⁻¹ at a total pressure of 0.15 mbar. A thorough analysis of the three lowest wavenumber fundamental bands, ν₃, ν₄ and ν₆, which fall in this region, has been carried out using a Hamiltonian model, which takes explicitly into account the numerous resonances affecting the ro-vibrational energy levels; especially the massive A-type Coriolis resonance between the out-of-plane wagging mode, ν₄, and the in-plane rocking mode, ν₆. These two modes are only separated by 0.83 cm⁻¹, and they are thoroughly mixed. From the fittings, the following band centers were derived: ν_o (ν₄)=990.18213(40) cm⁻¹, ν_o (ν₆)=991.02021(50) cm⁻¹ and ν_o (ν₃)=1059.20476 (30) cm⁻¹ where the uncertainties are one standard deviation. In addition, a number of relative line intensities were measured permitting the determination of relative values of the first-order transition moments and therefore relative band intensities for all three bands. Finally, a comprehensive list of line wavenumbers and relative intensities has been generated.     

Frequency measurements in the 9μm spectrum of CF3Br

Carbon dioxide laser saturation spectra of CF₃ Br have been explored with a view to hyperfine spectroscopy and references for frequency standards in the 9μm band of the carbon dioxide laser. Spectra have been obtained using the laser transitions 9R(16)-9R(30). and show many saturation features in each case. Several of the stronger features have been referenced directly to CO₂ frequencies with an estimated accuracy of 25 kHz. Spacings between the hyperfine components are also reported. This work represents some of the first data relevant to 9μm locking to molecular absorptions.     

Absolute line intensities measurements and calculations for the 5.7 and 3.6 μm bands of formaldehyde

The goal of this study is to achieve absolute line intensities for the strong 5.7 and 3.6 μm bands of formaldehyde and to generate, for both spectral regions, an accurate list of line positions and intensities. Both bands are now used for the infrared measurements of this molecule in the atmosphere. However, in the common access spectroscopic databases there exists, up to now, no line parameters for the 5.7 μm region, while, at 3.6 μm, the quality of the line parameters is quite unsatisfactory. High-resolution Fourier transform spectra were recorded for the whole 1600–3200 cm^?1 spectral range and for different path-length-pressure products conditions. Using these spectra, a large set of H₂CO individual line intensities was measured simultaneously in both the 5.7 and 3.6 μm spectral regions. From this set of experimental line strength which involve, at 5.7 μm the ν₂ band and, at 3.6 μm, the ν₁ and ν₅ bands together with nine dark bands, it has been possible to derive a consistent set of line intensity parameters for both the 5.7 and 3.6 μm spectral regions. These parameters were used to generate a line list in both regions. For this task, we used the line positions generated in [Margulés L, Perrin A, Janeckovà R, Bailleux S, Endres CP, Giesen TF, et al. Can J Phys, accepted] and [Perrin A, Valentin A, Daumont L, J Mol Struct 2006;780–782:28–42] for the 5.7 and 3.6 μm, respectively. The calculated band intensities derived for the 5.7 and 3.6 μm bands are in excellent agreement with the values achieved recently by medium resolution band intensity measurements. It has to be mentioned that intensities in the 3.6 μm achieved in this work are on the average about 28% stronger than those quoted in the HITRAN or GEISA databases. Finally, at 3.6 μm the quality of the intensities was significantly improved even on the relative scale, as compared to our previous study performed in 2006.     

Interaction of 3μm radiation with matter

Drilling of small holes into media containing O-H or C-H bonds with a 2.92m YAIO₃-Er laser is studied. In materials containing O-H bonds strong absorption allows small volumina to be heated with only marginal heat diffusion. Drilling with nearly diffraction-limited lateral resolution is achieved.     

Analysis of the Isotopic Composition of Exhaled Air by the Diode Laser Spectroscopy Method in the 2-μm Region for Diagnosis of Helicobacter pylori-Associated Diseases

Optics and Spectroscopy - To diagnose digestive diseases associated with Helicobacter pylori infection, we applied laser spectroscopic analysis of the 13СО2/12СО2 isotope...     

Assessment of the 200-μm Atmospheric Window for Ground-Based Astronomy

Submillimetre astronomy with ground-based instruments is currently restricted to spectral windows below 1 THz where the atmosphere is not very opaque. Recently, it was shown that supra-terahertz windows also unfold under very good atmospheric conditions, and could be explored for this effect. In particular, the 200 m window (1.5 THz) can transmit up to 30% on exceptionally dry weather at high-altitude sites. This study was conducted in parallel with the designs of THUMPER, a Two Hundred Micron Photometer for the James Clerk Maxwell Telescope, in Hawaii. Here we consider the weather conditions required and how often they arise, both by modelling the spectral transmittance of the atmosphere at 200 m and by analysing opacity data at 225 GHz. Implications for submillimetre astronomy are discussed. This study could benefit the ongoing analysis of other observation sites.     

Experimental investigation of the 2.1-μm single-mode Tm-Ho:KYF laser

We report on the development and comprehensive characterization of a room-temperature single-mode 2-m Tm-Ho:KYF laser. A maximum CW output power of 70 mW at the central wavelength of 2.078 m has been obtained. Using a 5-mm long intracavity birefringent filter the single-mode emission wavelength can be tuned over a range of 40 nm. Both frequency and relative intensity noise have been investigated showing a 1-ms emission linewidth of 600 kHz and an intensity noise spectrum that is quantum-noise limited for Fourier frequencies higher than 1 MHz. PACS 42.55Xi; 42.55Rz; 42.60Pk; 42.70Hj; 42.60Lh     

Analysis of the stimulated Raman spectrum of the ν16ν2 + ν18 Fermi dyad of benzene

Ionization-detected stimulated Raman spectroscopy was used to obtain high-resolution recordings of the two perpendicular bands of the benzene molecule centered at 1591.327 and 1609.518 cm⁻¹. The effective resolution was further enhanced by deconvolving the spectrum to a linewidth 0.003 to 0.004 cm⁻¹. Fine-tuning of the ionizing radiation made it possible to record the transitions belonging to each band separately, thus greatly simplifying the spectrum in the region of overlap. The strong ^sS and ^oO branches were, for the most part, completely resolved as were many lines in the weaker ^oP and ^sR branches and even in the central ^oQ and ^sQ branches. The observed bands belong to the E_2g fundamental ν₁₆ in nearly exact Fermi resonance with the combination ν₂ + ν₁₈. A detailed rovibrational analysis of the spectrum is reported. A perturbation detected in the ^sS_k branches of the lower-frequency band for K = 19 to 23 was identified as a quintic anharmonic resonance with the third overtone, 4ν₂₀, of the lowest lying fundamental ν₂₀, which is infrared- and Raman-inactive (species E_2u). Deperturbed spectroscopic constants for the interacting states are reported which reproduce the observed line positions with a standard deviation of 0.0013 cm⁻¹. The unperturbed origins of the ν₁₆ and ν₂ + ν₁₈ states are only 1.106 cm⁻¹ apart. The fundamental ν₁₆ was identified with the higher-frequency state with origin at 1600.976 cm⁻¹.     

High resolution analysis of the ethylene-1-C spectrum in the 8.4-14.3-μm region

Fourier transform spectra of mono-¹³C ethylene have been recorded in the 8.4-14.3-μm spectral region (700-1190 cm⁻¹) using a Bruker 120 HR interferometer at a resolution of 0.0017 cm⁻¹ allowing the extensive study of the set of resonating states {10¹, 8¹, 7¹, 4¹, 6¹}. Due to the high resolution available as well as the extended spectral range involved in this study, a much larger set of line assignments are now available. The present analysis has lead to the determination of more accurate spectroscopic constants, including interaction constants, than were obtained in earlier studies. In particular, the following band centers were derived: ν₀(ν₁₀) = 825.40602(30) cm⁻¹, ν₀(ν₈) = 932.19572(15) cm⁻¹, ν₀(ν₇) = 937.44452(10) cm⁻¹, ν₀(ν₄) = 1025.6976(14) cm⁻¹. Finally a synthetic spectrum was generated leading to the assignment of a number of ¹³C¹²CH₄ lines observed in an earlier heterodyne spectroscopic study.     

Dual-Frequency Generation in Quantum Cascade Lasers of the 8-μm Spectral Range

Results of an investigation of quantum cascade lasers of the 8-μm spectral range generating dual-frequency radiation at room temperature are presented. The dependences of radiation intensity for two lines of laser generation obtained as a result of investigation of the generation spectra revealed the presence of saturation and decay of the long-wavelength line of generation and linear growth of the intensity of the short-wavelength one. Based on analysis of the obtained data, a mechanism of the dual-frequency generation in the studied QCL samples is proposed Generation.     

Isotopic shift of the ground state of neon from the experimental results concerning the absorption of 0.63-μm laser radiation

Isotopic shifts of the 3s[3/2] ₁ ⁰ –2р ⁶(¹ S ₀) and 3s'–2р ⁶(¹ S ₀) transitions, equal, respectively, to 417 ± 20 and–98 ± 20 MHz, have been measured using the 0.63-μm radiation of a helium–neon laser and opto-magnetic resonances induced by the interference of the reactive components of fields in overlapping areas of the emissions of isotopic atoms. Combining these results with the absolute specific mass shift of the 3p[5/2]₂ level (–647 MHz), the isotopic mass shift of the ground state of neon equal to 3223 ± 30 MHz, and its specific mass shift equal to–9782 ± 30 MHz have been determined.     

Spectral measurements of high-temperature isotopic carbon dioxide in the 4.5- and 2.8-μm regions

High-resolution measurements have been made using the AFGL 2-m path difference Fourier transform spectrometer on isotopically enriched samples of carbon dioxide. Two regions were investigated: 2140–2320 and 3470–3770 cm⁻¹. The samples were observed in absorption at temperatures up to 800 K. Observed line positions to high rotational levels were obtained for 15 parallel bands with Δv₃ = 1 for the isotopic variants ¹³C¹⁶O₂, ¹³C¹⁶O¹⁸O, and ¹³C¹⁶O¹⁷O in the 4.5-μm region and for 23 bands of the type Δv₁ = 1, Δv₃ = 1 for the species ¹²C¹⁶O₂, ¹²C¹⁶O¹⁸O, and ¹²C¹⁸O₂ in the 2.8-μm region.     

A high-resolution study of the ν3 and 2ν80 bands of propyne

The ν₃ and 2ν₈⁰ parallel bands of propyne (methyl acetylene) at 2137.88 and 2066.33 cm⁻¹ have been studied at 0.006 cm⁻¹ resolution. Their Fermi resonance and interaction with the ν₈ + 2ν₉, ν₇ + ν₉, and ν₈ + ν₉ + ν₁₀ levels have been investigated. Molecular constants were determined from the assignment of 1150 lines. However, the rms error of 0.0028 cm⁻¹ showed the presence of additional perturbations which cannot be uniquely identified.     

Analysis of the hot bands in the 2ν9 band region of propyne-d3

The rovibrational spectrum of 2ν₉ band of CD₃CCH is overlapped by two prominent hot bands identified as (2ν₉⁰+ν₁₀^±1)(E)←ν₁₀^±1(E) and 3ν₉^±1(E)←ν₉^±1(E), where ν₁₀ and ν₉ are the degenerate CCC and CCH bending fundamental vibrations, respectively. Assignment of lines to the transitions of these hot bands were carried out with the help of the high-resolution spectra recorded at ∼195 K and at room temperature. Molecular parameters for these hot bands have been obtained from the rotational analysis of the partially resolved K-structure lines. Only Q-head of the third hot band , originating from the lower 2ν₁₀ state could be identified.