Gamma-ray angular correlations perturbed by a stochastic Gaussian-Markov process

Self-broadening of principal series lines of rubidium has been studied using a steel absorption tube heated up in an electric furnace. Line profiles were obtained with a grating spectrograph of high resolution in the temperature range 350–420 °C corresponding to number densities of 18.6–119 · 10¹⁵ cm^?3. The half-widths of the lines disagree with classical impact calculations using dipol-dipol interaction but approach nearly the asymptotic value of the quantum-mechanical polarization theory of Reinsberg.     

Van der Waals broadening of argon absorption lines

Van der Waals broadening coefficients for Ar absorption lines have been measured using the resonant Faraday effect. These coefficients have the values of 2·9 ± 0·8, 2·4 ± 0·3, 1·9 ± 0·2 (in units of 10^?20 cm^?1 ?cm^?3) for the lines 6965 Å, 7067 Å, 7635 Å and 8115 Å, respectively, respectively. The measured coefficients are in reasonable agreement with measurements carried out on Ar emission lines and with theoretical calculations.     

Absorption spectra and Zeeman effects of Tm3+ in CaF2

The absorption spectra of Tm³⁺ in CaF₂ were analyzed by the concentration series method at 4·2^°K. Systems of lines, belonging to Tm³⁺ion centers of different structure, are isolated from the general spectra. Some of structures of Tm³⁺ ion centers were made clear by studying optical Zeeman effects and a change of absorption lines during thermal treatment. The tetragonal crystal field parameters and g-value of the upper state are also discussed.     

Oscillator strengths of the first forbidden lines of rubidium

The oscillator strengths of the 5s-4d first forbidden lines of rubidium at 5165 Å were determined by performing CW tunable dye laser absorption measurements. Measured oscillator strengths of 8.06±0.48×10^-7 and 5.38±0.31×10^-7 for the ²D_{$\text{5}\text{2}$} and ²D_{$\text{3}\text{2}$} states, respectively, are compared with previously published values.     

Spectroscopic Studies of Indium Plasma Produced by Fundamental (1,064 nm) and Second (532 nm) Harmonics of an Nd:YAG Laser

In this paper, we present spectroscopic studies of a laser-induced indium (In) plasma produced by fundamental (1,064 nm) and second (532 nm) harmonics of an Nd:YAG laser along with the characteristics determined by plasma parameters. The electron temperature is determined using four lines of neutral indium at 260.17, 271.02, 275.38, and 325.85 nm, in view of the Boltzmann plot method. The temperature varies from 6,470 K at 0.05 nm to 4,990 K at about 2 mm from the target surface for the fundamental wavelength and from 6,250 to 4,880 K for the second harmonic. The electron density is ±300 calculated using the Stark broadened profiles recorded at laser pulse energy 130 mJ (for fundamental) and 72 mJ (for second harmonic) as 5:8·10¹⁶ and 6:9·10¹⁶ cm^?3, respectively. These values decrease to 3:5·10¹⁵ and 4:9·10¹⁵ over a distance of 2 mm from the target surface, respectively. Moreover, we study the variation of N _e as a function of laser irradiance as well as its spatial variation from the target surface.     

Line strength and halfwidth measurements from far infrared absorption spectra: Carbon monoxide

A method for deriving Lorentzian line shape parameters (line strengths and halfwidths) from absorption spectra taken at two different path lengths is discussed. Far i.r. absorption spectra of carbon monoxide are analysed to yield line strengths and halfwidths for the rotational transitions J″ = 3 through J>″ = 9. Experimental errors are discussed, and the value for the dipole moment derived from the line strengths, 0·108±0·005 D, is in agreement with the microwave value within experimental uncertainty. The Lorentzian halfwidths are compared, where appropriate, with two recent determinations of these quantities. Lorentzian halfwidths are also derived from absorption spectra taken at long path length using theoretical line strengths based upon μ_co = 0·112D.     

High-resolution spectroscopy of the oxygen A band

A high-resolution spectrometer incorporating a narrow linewidth (<10⁻⁴ cm⁻¹) tunable dye laser has been used to measure absorption profiles of 54 spectral lines of the b¹Σ_g⁺ (ν = 0) ← X³Σ_g⁻ (ν = 0) band of molecular oxygen (the “A band”) at pressures up to one atmosphere. A least-squares fitting procedure was used to compare the observed line profiles to four types of line profiles, including the Voigt function, two Dicke-narrowed profiles, and a speed-dependent Voigt profile. Clear deviations are shown between the observed profiles and the standard Voigt function. The other profiles all compare favorably with the observed lineshapes. Values of the line strengths and self-broadening coefficients, determined from least-squares fitting to the Galatry collisionally narrowed profile, are presented in tabular form. The distribution of line strengths is compared to expressions available in the literature. The self-broadening coefficients are compared with the measurements of several other investigators. Several lines have also been measured in air, and air broadening is compared with self-broadening.     

Measurement of Ar(I) and Ar(II) transition probabilities in LTE ARC plasmas

The transition probabilities of two Ar(I) lines and one Ar(II) line have been measured in emission on wall-stabilized argon arc plasmas (0·5×10⁵?p, Nm^-2?3×10⁵; 10,000?T, K?20,000; 10²²?N_e, m^-3?5×10²³) using the “method of best fit (MBF)”. The results (without line-wing correction) are for Ar(I) at 714·7 nm, A_nm=5·66×10⁵ s^-1±5%; for Ar(I) at 430·0 nm, A_nm=3·40×10⁵ s^-1±5%; for Ar(II) at 480·6 nm, A_nm=8·82×10⁷ s^-1±7%. These values were not influenced by deviations from LTE, which have been observed at electron number densities n_e?10²³ m^-3. The small uncertainties were achieved after careful corrections of different sources of error.     

Far infrared optical properties of free carriers in GaAs

Transmission and reflection measurements over the frequency range 17–200 cm^?1 were made on GaAs with electron concentrations of 1·0 and 4·9 × 10¹⁶ cm^?3. The plasma frequencies of the samples fall within the measurement range. When values of the free carrier absorption coefficient α and the real refractive index n as derived from the data are plotted in the form (αn)^?1 vs (frequency)², the plots are linear, in excellent agreement with Drude theory. Deduced values of effective mass, relaxation time and mobility agree with published values and with a d.c. drift measurement.     

Change of phonon dispersion curves due to interstitials in Al

An experimental investigation of the profiles of the 4471 Å and 4922 Å lines in the afterglow of an high density plasma of helium produced by laser is reported. The measured profiles of these two neutral helium lines and their forbidden components are given at electron densities between 5 · 10¹⁶ cm^?3 and 2 · 10¹⁷ cm^?3 and for electron temperature between 3 and 4 eV.     

Confirming Sγ products by blending isotopic doublets of HCl

Experimental confirmation is reported of a published technique, ⁽²⁾ applicable to the square root region which specifies the degree to which two Lorentz absorption lines, not necessarily equal, overlap. It also specifies the deficiency, γ, of the aggregate equivalent width of the blend from its value when the two lines are completely independent. The experiment was conducted at room temperature using pure HCl gas in a 3·34 m path at pressures from 2 to 750 torr. It consisted of sequentially pressure blending fundamental band isotopic doublets. The blended equivalent width of each doublet was compared to predictions from the aforementioned theory as a function of pressure, using previously published values of S and γ as the basis for its application.Published line strength values for the HCl fundamental band agree well only in the upper R (J≥7) branch. These were used to test the procedure. Predictions based upon divergent line strengths in the remainder of the band were then compared to the experimental results and confirm the accuracy of the Sγ products of Benedictet al.⁽¹⁾A polynomial representation of the Ladenburg-Reiche function is given which is useful in extending the procedure of Ref. (2) to the linear region.Finally, a new experiment is described, based upon the confirmed theory, which allows the validity of the Lorentz shape to be assessed as a function of pressure for various foreign broadeners and interaction potentials. Application to cometary abundance determinations is also discussed.     

Line intensities of methane in the 2700–2862-cm−1 region

Individual strengths and wavenumbers of 2080 methane absorption lines have been measured between 2700 and 2862 cm^?1 at an average resolution of 0.023 cm^?1 using a grating spectrometer. The results include all lines with strengths greater than 3 × 10^?5 cm^?2 atm^?1 observable at 296 K with a maximum path of 32 m and a pressure of 4 Torr.     

Stark broadening parameters of Si I,Si II and Si III lines

Spectral lines emited by first three ionisation species of silicon were studyed in a wide range of plasma parameters. The silicon was present as an impurity in the argon plasma created in an electromagneticT tube. Four various condenser bank energies give the plasma in a range of temperatures 8700 to 16400°K and electron concentrations 2.95·10¹⁷ cm^?3to 5.6·10¹⁷ cm^?3. Measured line widths and shifts were compared with theories of Griem [1, 2] and Sahal Brechet [3, 10]. The agreement is reasonably good, the measured values are in general smaller than calculated ones.     

Experimentally determined oscillator strengths and linewidths for the Schumann-Runge band system of molecular oxygen—II. The (2-0) to (5-0) bands

Experimental oscillator strengths and predissociation linewidths have been measured at room temperature for the (2-0) to (5-0) Schumann-Runge bands of molecular oxygen using the Adelaide 6 m vacuum ultraviolet monochromator operated at a resolution of about 0.06 Å. Photoelectric detectors were used to measure the ultraviolet absorption at normally two different gas pressures for 37 groups of rotational lines, and the resulting data were interpreted using an equivalent width type of analysis. The variation with N″ of the oscillator strengths within each band was found to be smaller than that measured earlier for the higher vibrational bands. Measured oscillator strengths agree well with previously accepted values except for the (3-0) band, while the linewidths of the present work agree well with recent theoretical values for the (3-0) and (4-0) bands but are larger for the (2-0) and (5-0) bands. A modification was performed on the parameters of a recent theoretical predissociation model to produce excellent overall agreement between experimental and theoretical linewidths from ν' = 2 to 14. The present work provides results which can be used to construct accurate synthetic absorption profiles for studies of the atmospheric absorption of ultraviolet radiation by the Schumann-Runge bands.     

Experimentally determined oscillator strengths and linewidths for the Schumann-Runge band system of molecular oxygen—I. The (6-0)–(14-0) bands

Experimental oscillator strengths and predissociated linewidths have been measured at room temperature for the (6-0)–(14-0) Schumann-Runge bands of molecular oxygen using the Adelaide 6 m vacuum u.v. monochromator operated at a resolution of about 0.06 Å. Photoelectric detectors were used to measure the u.v. absorption at two different gas pressures for 138 groups of rotational lines distributed throughout the (6-0)–(14-0) bands and the resulting data were interpreted using an equivalent width type of analysis. Experimental measurements of the variation with N″ of the oscillator strengths within each band have been obtained for the first time. Measured oscillator strengths are found to be somwhat higher in general than previously reported values with a slightly faster decrease as N″ increases than is predicted theoretically. The mean predissociated linewidths obtained for each band show a smooth variation with v′, agreeing well with other results for v′=12?14 and lying between previously reported experimental and theoretical values for v′=6?9. The present work provides results which can be used to construct highly accurate synthetic absorption profiles for studies of the atmospheric absorption of u.v. radiation by the Schumann-Runge bands.     

Line strengths and self-broadened linewidths of N2O in the 2-μm region: 2400-0000 and 0112-0000 transitions

The strenghths and self-broadened linewidths of the parallel 24⁰0-00⁰0 and perpendicular 01¹2-00⁰0 bands of N₂O have been measured with a precision better than 3%, using a deconvolution procedure. For both transitions, the coefficient of the vibration-rotation interaction polynomial, the values of the rotationless dipolar transition moment, and the band intensity have been calculated from the line strengths. For the total intensity the values found are S_00⁰0²⁴⁰⁰ = (1.325 ± 0.021) × 10^?2 cm^?2·atm^?1 and S_00⁰0⁰¹¹² = (1.209 ± 0.018) × 10^?2 cm^?2·atm^?1.     

Line strengths,spin-splittings,and forbidden transitions in the (101) band of 14N16O2

Measurements of line strengths in the (101) and (111)-(010) bands of ¹⁴N¹⁶O₂ have been made at a resolution of 0.02 cm^?1 in the region 2863 to 2934 cm^?1. The strength data in the (101) band were analyzed to determine a vibrational band strength and coefficients of the F factor. Each subband for K_?1 ≤ 9 was analyzed separately and all the F-factor coefficients in terms of the rotational quantum number, N, were found to be too small to be of significance. However, F was found to be dependent on K_?1 and the experimentally determined subband strengths were least-squares fitted to the expression S_v⁰·F, where S_v⁰ = 68.3 cm^?2 atm^?1 at 296 K and F = 1 + (2.899 × 10^?3)K_?1 + (4.08 × 10^?3)K_?1² ? (2.34 × 10^?4)K_?1³. The integrated strengths for the (101) and (111)-(010) bands were found to be 70.9 ± 2.3 and 2.7 ± 0.3 cm^?2 atm^?1 at 296 K, respectively. Also included in this study are measurements of line center positions in the two bands and spin-splittings in the (101) band. Recent frequency measurements of lines with K_?1 ≤ 8 in the (101) band have been made at a resolution of 0.0033 cm^?1 by V. Dana and J. P. Maillard (J. Mol. Spectrosc.71, 1–4) (1978)) for the region above 2889 cm^?1 and our values are in excellent agreement with theirs. Separations of the split lines measured in this work (K_?1 ≤ 10) agree well with calculated values using expressions which include the η_aaaaK_?1⁴ term with η′_aaaa = ?1.70 ± 0.15 × 10^?4 cm^?1 as derived for the (101) state. Three forbidden (ΔN ≠ ΔJ, ΔK_?1 = 0) transitions in the (101) band were observed with their identifications based on the agreement between measured and calculated line positions and strengths.     

Optical absorption edge in SnS

Optical absorption in single crystals of tin sulfide has been studied at many temperatures between 100 and 300 °K, in the wavelength range 2·2–0·8 μ. From the interference fringe patterns the absorption coefficient, reflection coefficient and index of refraction as a function of wavelength were determined for two light polarizations (ε∥a and ε∥b). From an analysis of the data, indirect band gaps of 1·142 and 1·095 eV were found for the two directions of polarization. Also it was found that the phonon assisted transitions required the participation of two phonons at different energy thresholds with energies 0·033 or 0·038 eV and 0·082 or 0·113 eV, with reference to the two axis. The temperature dependence of the indirect band gap for each direction of light polarization is linear with a slope ?4·05 × 10^?3eV and ?4·37 × 10^?3 eV respectively.     

Diffusionskonstante und charakteristische Absorption vor der Bandkante von Mn in ZnO-Kristallen

ZnO single crystals were doped with Mn and Co by diffusion. In the temperature range from 1400–1600 K the Mn and Co-diffusion-constants were determined:D _Mn=3.2 · 10^?3 exp (?2.87 eV/kT) cm² sec^?1 andD _Co=1·10exp(?3.98 eV/kT) cm² sec^?1. The Mn doped ZnO crystals show a characteristic colour due to an absorption near the intrinsic absorption edge. The corresponding absorption spectra were measured forE⊥c andE∥c. A discussion of different absorption mechanism shows that a charge-transfer transition is responsible for this absorption.     

Measurement of intensities of multiplets in the 2ν3-band of methane at low temperatures

The integrated intensities of the multiplets P(1)–P(10), R(0)–R(9), and of the Q-branch in the 2ν₃-band of ¹²CH₄ have been measured at 102°K, 152°K, 202°K, 251°K, and 300°K. Comparison of our data with theoretical line strengths confirms, at all of the temperatures mentioned, the intensity anomalies observed by Margolis⁽⁵⁾ for lines in this band. The integrated intensity of the 2ν₃-band is found to be S_v = (1·76±-0·04)(300/T (°K)) cm^?2 atm^?1.