Measurement at different temperatures of absolute intensities,line half-widths,and broadening by Ar and N2 for the 3001II←0000 band of CO2

Absolute intensities, self-broadening coefficients, and foreign-gas broadening by Ar and N₂ were measured at temperatures of 197, 233 and 294 K for the 30⁰1_II←00⁰0 band of CO₂ at 6348 cm^-1. Also, the intensity parameters and total band intensity were calculated. We obtained for the vibration-rotation interaction factor the value F(m) = 1 + (0.26 ± 0.06) × 10^-2m + (0.92 ±0.32 × 10^-4 m²; for the purely vibrational transition moment, we found ¦R₀₀₀₀^3001_II¦к(0.4351 ± 0.0014)()10^b3 debye; and, for the total band intensity at STP conditions, S_band(30⁰1_II←00⁰0)_STP = 1255 ± 9 cm^-1 km^-1 atm^-1.Self-broadening coefficients at 197 and 294 K were also measured, as well as broadening by Ar and N₂. Foreign-gas-broadening efficiencies (Ar and N₂) were determined. Finally, a comparison is made with measurements by other authors and with theoretically calculated values.     

Pressure-Broadened Linewidth Measurements in the ν2Band of the CH3Radical

Pressure broadening coefficients for an infrared transition of the methyl radical have been measured for the first time. CH₃radicals, generated by pyrolyzing di-tert-butyl peroxide in a flow of either N₂or Ar, were probed using a tunable diode laser and a multipass absorption cell. The Lorentz half-width of theQ(6,6) line of the ν₂band of CH₃at 607.024 cm⁻¹was measured as a function of pressure at 295 K. The broadening coefficients (HWHM) areb(Ar) = 0.0310 ± 0.0012 cm⁻¹atm⁻¹andb(N₂) = 0.0390 ± 0.0020 cm⁻¹atm⁻¹. These coefficients are lower than those for CH₄–Ar, N₂broadening. This may be due to a lower polarizability or smaller effective hard collision diameter for CH₃relative to CH₄.     

Tunable diode laser measurements of spectral parameters of HCN at room temperature

A tunable infrared diode laser was used to record 17 fully resolved vibration-rotation transitions in the v₁ fundamental band of HCN at 3μ. The experiments were conducted in an absorption cell on room temperature mixtures of HCN diluted by N₂ and Ar. The v₁ fundamental band strength of HCN was determined to be 267±8 cm^-2 atm^-1 at 273.2 K. Small but significant reductions in the residual errors were obtained by using the Galatry profile rather than the Voigt profile to fit the experimentally recorded line shapes. Collisional broadening and narrowing parameters were determined simultaneously from Galatry profile fits to the data. The collision-broadened linewidths of HCN lines in N₂ and Ar were determined as a function of rotational quantum number of transitions ranging from P(14) to R(14) (3268.22-3353.29 cm^-1). The optical diffusion coefficients of HCN in N₂ and Ar at 300 K were determined from the collisional narrowing parameters and were 0.074±0.01 and 0.016±0.03 cm²s^-1 respectively.     

Measurement of collision broadening of the P1(5) line of (0,0) band of OH AΣ←XΠ transition at high temperatures

Even for the well-studied and ubiquitous species, OH, the current state of theoretical development of broadening theory does not allow extrapolation from low-temperature laboratory measurements to the range of practical combustion devices. We performed a series of experiments at typical combustion conditions to determine the collision broadening of the P₁(5) line of the (0,0) band of OH A²Σ⁺←X²Π transition by Ar in shock-heated H₂-O₂-Ar mixtures and by air in H₂-air flames over a wide range of stoichiometry (φ=0.01-10.0), temperature (T=780-2440 K), and pressure (p=0.7-10.0 atm). The values of the collision width, Δν_C, were acquired by fitting Voigt profiles to the measured spectral line shapes in flames and to the peak absorption coefficients (k_ν0) in shock tube experiments. Collision broadening parameters (2γ_Ar, 2γ_N2, and 2γ_H2O) were then calculated assuming the linear dependence of Δν_C with pressure—the 2γ_N2 and 2γ_H2O values were inferred from 2γ_Air and the equilibrium concentration of N₂ and H₂O of a given flame. The temperature dependences of 2γ_i in our temperature range are, respectively, 1.0, 0.75, and 0.87 for Ar, N₂, and H₂O. The collision broadening cross sections (σ) deduced from 2γ_i values are expressed with an assumed form, σ_i(T)=σ_i,₀(T₀/T)^k, T₀=1000 K: for Ar, σ_Ar,0=63.3 (Ų), k=0.50; for N₂, σ_N2,0=68.0 (Ų), k=0.25; for H₂O, σ_H2O,0=188.8 (Ų), k=0.37.     

Pressure shift and broadening of 110-101 water vapor lines by atmosphere gases

This paper is devoted to the measurement of pressure shift and broadening parameters of water-vapor lines of the pure rotational transition 1₁₀-1₀₁ in the ground vibrational state of H₂¹⁶O at 556.936 GHz, H₂¹⁷O at 552.02 GHz, H₂¹⁸O at 547.676 GHz, and the vibrationally excited state v₂=1 line of H₂¹⁶O at 658.003 GHz. The broadening coefficients of the line at 556.936 GHz (for N₂ and O₂ as perturbing gases) coincide within the errors with the values obtained recently by Seta et al. [Pressure broadening coefficients of the water vapor lines at 556.936 and 752.033 GHz. JQSRT 2008;109:144-50] by means of a very different technique (THz-TDS). Pressure shift and broadening for other lines were measured for the first time. Comparison of our results with previous measurements and theoretical calculations is presented.     

Mößbauereffekt in Eisenstilben und FeCl2·H2O

Using Mößbauer effect measurements in the temperature range between 3 °K and 310 °K the magnetic fields at the nucleus in iron-stilbene, FeCl₂·H₂O and FeCl₃ are determined to beH _T=0=(250±10) kOe, (252±18) kOe and (468±10) kOe; a Néel-temperature ofT _N=(23±1) °K is measured for iron-stilbene. The electric quadrupole splittings atT=0 °K for iron-stilbene and FeCl₂ ·H ₂ O, ΔE=(+2.52±0.02) mm/sec and (+2.50±0.05) mm/sec, yield electric field gradients at the iron nucleus ofq _z=+9.7·10¹⁷ V/cm² and +9.6·10¹⁷ V/cm², whereq _z⊥H; Debyetemperatures of θ=162 °K and 188 °K are obtained. The energy of the excited 3d-electron levels in iron-stilbene is estimated to Δ₁=309 cm^?1 and Δ₂=618cm^?1 as deduced from the temperature dependence ofΔE. In contrast to the suggestion ofEuler andWillstaedt bivalence of the iron in ironstilbene is found; its composition is shown to be 4(FeCl₂ ·H ₂O)·stilbene.     

Absorption measurements of H2O at high temperatures using a CO laser

Absorption of CO laser radiation (v = 8→7, J = 14→15 transition at 1901.762 cm^-1) by H₂O has been studied in shock-heated H₂/O₂/Ar mixtures over the temperature range 1300–2300 K. This laser transition is nearly coincident with the v₂-band 12_3,10←11_2,9 transition of H₂O at 1901.760 cm^-1, thereby providing a convenient and sensitive absorption-based H₂O diagnostic useful for studies of combustion. The collision-broadening parameter for this H₂O line, due to broadening by Ar, was determined to be 2γ (cm^-1atm^-1) = 0.027 (T/1300)^-0.9 in the temperature range 1300–2300 K. Calculations of the H₂O absorption coefficient (at 1901.762 cm^-1) based on this expression for 2γ are presented for the temperature range 300–2500 K and pressure range 0.3–1 atm.     

Tunable infrared diode laser measurements of line strengths and collision widths of 12C16O at room temperature

A tunable diode laser was used to scan 33 vibration-rotation lines in the fundamental band of CO in room-temperature CO-N₂ and CO-Ar mixtures. Each absorption record was fitted with a Voigt profile from which the line strength and collision width were determined. The fundamental band strength of ¹²C¹⁶O at 273.2°K was determined to be 283±4 cm^-2 atm^-1. Results are also presented for the rotational quantum number dependence of the collision width for broadening by N₂ and Ar.     

Tunable diode laser measurements of the band strength and collision halfwidths of nitric oxide

The strength of the fundamental absorption band of nitric oxide at 5.3 μm and collision halfwidths of nitric oxide lines broadened by nitrogen, argon, and combustion gases were measured in absorption cell, flat flame and shock tube experiments using a tunable diode laser. Room temperature absorption measurements were made in an absorption cell filled with NO/N₂ or NO/Ar mixtures or with probe-extracted combustion gases. High temperature (to 2500 K) absorption measurements were performed for NO in N₂ and NO in Ar using a shock tube, and for NO in combustion gases using a flat flame burner.Absorption measurements were made on lines from 1860–1925 cm^?1, ($\text{Ω=}\text{1}\text{2}$ and $\text{3}\text{2}$,P($\text{5}\text{2}$-R ($\text{29}\text{2}$)) resulting in a band strength of 123±8 cm^-2 atm^?1 at 273.2 K. Collision halfwidth dependencies for each broadening species were examined as a function of rotational quantum number and temperature.     

Quenching of excited strontium atomic state measured in H2- and CO-flames

The efficiency of resonance fluorescence, Y, of the strontium resonance line (¹P₁→¹S₀ transition) at 4607.33 Å was measured in CO/N₂O, CO/O₂/Ar, and H₂/O₂/CO₂/N₂ flames at atmospheric pressure. From these data, the specific quenching cross sections, σ_qu, for CO₂ and CO were found to be (60 ± 10) Ų and  (300 ± 60) Ų, respectively. The experimental cross sections were confronted with the intermediate ionic-state curve-crossing model and chemical quenching model, respectively.     

Absorption profiles of HCl for the J = 1-0 rotational transition: Foreign-gas effects measured for N2, O2, and Ar

Line profiles of the J = 1-0 transition of the hydrogen chloride, H³⁵Cl and H³⁷Cl isotopomers, were measured with a BWO-based submillimeter-wave spectrometer at AIST in real form: three hyperfine transitions for each isotopomer, i.e., total six lines at 625 and 626 GHz. The effect of foreign gases on the broadening and shift was determined for N₂, O₂, and Ar. The modified Voigt function was applied as the line shape function for preliminary analysis, where the collisional-narrowing effect was clearly observed. In the final analysis, we applied the Galatry function and determined the integral intensity, line center position, Lorentzian width, and contraction parameter for each absorption line. The magnitudes of the foreign-gas pressure-broadening coefficients decrease in order of N₂, O₂, and Ar. The line-shift coefficients were clearly observed, the magnitudes of which decrease in order of Ar, O₂, and N₂. The pressure dependence of contraction parameter was determined, although with poor precision.     

Some nuclear and atomic properties of201Hg determined by conversion electron spectroscopy

Conversion electron measurements with an electrostatic spectrometer proved the existence of the 1,565±6 eV transition in²⁰¹Hg. The conversion intensity ratios,N ₁/N ₂ =1.2±0.2,N ₁/N ₃=1.1±0.2,N ₂/N ₃=0.92±0.15,N ₄/N ₃=0.03± 0.02 andN ₅/N ₃=0.04 ±0.02 were determined. These values agree with our calculations for the M1±E2 multipolarity with theE2/M1 mixing ratioδ ²=(l.l±0.3)xl0^?4 and exclude all pure multipolarities withL≦4. The total conversion coefficient for the aboveM1 +E2 mixture was evaluated to be (4.7±0.7)× 10⁴. The reducedB(M1, 1/2→3/2) probability was derived to be (3.9 ±1.2) × 10^?3 (e?/2Mc)². The natural widths of theN-subshell conversion lines in mercury were found to beΓ(N ₁)=8.3± 1.5,Γ(N ₂) =5.8±1.5 and Γ(N ₃) =6.5±1.0 eV. Monte Carlo calculations of electron scattering in matter yielded the conversion line shapes in qualitative agreement with the experiment.     

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.     

Low-energy transition depopulating the isomeric 8+ level in 208Po

Conversion electron measurements of the low-energy transition depopulating the isomeric 8⁺ level in ²⁰⁸Po yielded E_γ = 4025 ± 20 eV and the conversion intensity ratios N₁/N₂ ? 0.2, N₂/N₃ = 0.75 ± 0.10, N_4.5/N₃ ? 0.2, O/N₃ = 0.35 ± 0.10, P/N₃ ? 0.1 and N₃/M₃ = 0.4 ± 0.2. These ratios are in accord with our calculations for the E2 multipolarity and exclude all other multipolarities with L ≦ 4. The total conversion coefficient was calculated to be 1.31 × 10⁷.     

Line strength and collisional broadening coefficients of H2O at 2.7 μm for natural gas quality assurance applications

We employed tunable diode laser absorption spectroscopy to measure the line strength, the methane (CH₄), ethane (C₂H₆) and the propane (C₃H₈) broadening coefficients for the 523–422 H₂O transition at 3619.61 cm^?1. Water amount fractions generated by a stable and accurate humidity transfer standard, traceable to the SI units via the German national humidity standard, were used to calibrate the spectroscopic line strength measurements. We focus on the traceability of the measured line data to the SI and on uncertainty assessments following the guidelines of the Guide to the Expression of Uncertainty in Measurement. We determined the line strength to be (8.42 ± 0.07)×10^?20 cm^?1/(cm^?2 molecule) corresponding to a relative uncertainty of ±0.8%. To the best of our knowledge, we report the first methane, ethane and propane broadening coefficients of (8.037 ± 0.056)×10^?5 cm^?1/hPa, (9.077 ± 0.064)×10^?5 cm^?1/hPa and (10.469 ± 0.073)×10^?5 cm^?1/hPa for the 523–422 H₂O transition at 3619.61 cm^?1, respectively. The relative combined uncertainties of the stated CH₄, C₂H₆ and C₃H₈ broadening coefficients are in the ±0.7% range.     

High resolution polarization spectroscopy and laser induced fluorescence of CO<Subscript>2</Subscript> around 2μm

High resolution Infrared Polarisation Spectroscopy (IRPS) and Infrared Laser Induced Fluorescence (IRLIF) techniques were used to probe CO₂/N₂ binary gas mixture at atmospheric pressure and ambient temperature. The probed CO₂ molecules were prepared by laser excitation to an overtone and combination ro-vibrational state (12⁰1, J=15) of CO₂, centred at 4988.6612 cm^-1. IRPS and IRLIF line profiles were recorded for several CO₂/N₂ binary mixtures. The observed IRLIF line shapes have the expected Lorentzian form while the observed IRPS line shapes are narrower by a factor of two than those recorded with the IRLIF and appear to have a Lorentzian-cubed profile. The recorded line profiles provide measurements of the pressure-broadening coefficient directly at atmospheric pressure. The Full-Width-Half-Maxima (FWHM) pressure broadening coefficients are measured, based on IRLIF, to be 0.2174±0.0092 cm^-1atm^-1 and 0.1327 ±0.0077 cm^-1atm^-1 for self- and N₂ collision broadening, respectively. The broadening coefficients obtained based on IRPS were measured to be ~8% larger than those obtained with IRLIF.     

The specific heat of CeAl2 between 0.02 and 1 K

We report specific heat measurements on a CeAl₂ single crystal between 0.02 and 1 K. Above 0.08 K, we found C₀ = γT + βT³ with γ = (130±0.5) mJ/K²mole and β = (142±1) mJ/K⁴mole in good agreement with previous results above 0.3 K. Below 0.08 K, an excess specific heat C_N = αT^?2 with α = (6.4±1) mJK/mole was detected and interpreted in terms of hyperfine splitting of the Al²⁷ nuclear states. Our results suggest that in CeAl₂ (complex) antiferromagnetism coexists with the Kondo effect at least down to 20 mK.     

Radiative lifetimes and electronic quenching rate constants for single-photon-excited rotational levels of no (A2Σ+, ν′ = 0)

A narrow-band, frequency-doubled, tunable dye laser has been used to excite fluorescence from the A²Σ⁺, ν′ = 0 state of NO. Collision-free lifetimes were measured for 21 different K′ levels giving a mean radiative lifetime τ = 217 ± 4 ns. Electronic quenching rate constants of NO (A²Σ⁺, ν′ = 0) were measured for O₂, N₂, H₂O, CO₂ and Ar. No dependence of the quenching-rate constant on the initially excited rotational level was observed.     

Magnetic transitions in K2MnCl4·2H2O

Results of (dM/dH) measurements on tetrahedral K₂MnCl₄·2H₂O as a function of temperature and magnetic field, are presented. An antiferromagnetic transition along the tetragonal axis is observed at T_N = (3.05±0.05) K. The H-T magnetic phase diagram was completely determined, and shows the usual characteristics of that of a low anisotropy antiferromagnet. The T = 0 critical fields are compatible with the values H_E = (29.2±0.3) kOe and H_A = (5.9±0.6) kOe for the exchange and anisotropy fields.     

Experimental natural lifetime determination of the Ar(II) lower laser levels

The natural lifetimes of the (³P)4s²P_3/2,1/2 levels of the Ar(II) spectrum have been determined from the natural broadening of argon lines, measured with a Fabry—Pérot interferometer. The natural broadening was determined from the lines with wavelengths of 4880 and 4965 Å by comparing them with the lines at 4806 and 5009 Å having negligible natural broadening. The natural lifetime of the 4s²P_3/2 level appeared to be τ = 0.19 (±6%) ns and of the 4s²P_1/2 level τ = 0.18 (±15%) ns. These values are about 1.5 to 2 times as small as those determined by other authors either experimentally by using a Fabry—Pérot interferometer by the method of Ballik, or calculated using intermediate coupling.The differences between the two experimental methods are discussed.