Rovibrational Intensities of the (00(0)3) <-- (10(0)0) Dyad Absorption Bands of (12)C(16)O(2).

Absolute line intensities of (12)C(16)O(2) are experimentally measured for the first time for the (00(0)3)(I) <-- (10(0)0)(II) band at 5687.17 cm(-1) and the (00(0)3)(I) <-- (10(0)0)(I) band at 5584.39 cm(-1). The spectra were obtained using a Bomem DA8 Fourier transform spectrometer and a 25-m base-path White cell at NASA-Ames Research Center. The rotationless bandstrengths at a temperature of 296 K and the Herman-Wallis parameters are S(0)(vib) = 6.68(30) x 10(-25) cm(-1)/(molecule/cm(2)); A(1) = 1.4(9) x 10(-4), and A(2) = -1.1(5) x 10(-5) for the (00(0)3)(I) <-- (10(0)0)(II) band and S(0)(vib) = 6.07(22) x 10(-25) cm(-1)/(molecule/cm(2)); A(1) = 5.2(1.5) x 10(-4) and A(2) = -4.0(7) x 10(-5) for the (00(0)3)(I) <-- (10(0)0)(I) band.

The NO Vibrational Fundamental Band: O2-Broadening Coefficients.

The first measurements of O2 broadening of NO lines is reported. For the NO fundamental vibration-rotation band, polynomial representations for this broadening at 299 K are given for Omega = 32 and Omega = (1/2) e and f transitions, respectively: gamma3/2(|m|) = 0.06463 - 0.00262|m| + 0.000147|m|2 - 0.00000327|m|3, gammaf1/2 (|m|) = 0.06515 - 0.00381|m| + 0.000271|m|2 - 0.00000665|m|3, and gammae1/2(|m|) = 0.06433 - 0.00343|m| + 0.000214|m|2 - 0.00000497|m|3. These broadening coefficients are on the order of 17% smaller than the comparable coefficients found for N2 broadening of NO. Copyright 1998 Academic Press.

Zeeman Tuning Rates for Q-Branch Transitions in the nu3 Band of NO2

Zeeman tuning rates have been measured for Q-branch transitions in the nu3 band of NO2 ( approximately 1610 cm-1) for magnetic fields of up to 564 Gauss. The average measured tuning rate is 0.1815(53) x 10(-3) cm-1/Gauss with no dependence on Ka within the approximately 3% standard deviation. Despite significant spin-rotation interaction between several of the observed levels the result agrees with the simple linear model for Hunds case (b) molecules (tuning rate = 2µogs = 0.18696 x 10(-3) cm-1/G), which neglects the spin-rotation interaction between different J states. The Zeeman effect is analyzed in a full treatment of the Hamiltonian, including spin-rotation interaction, in order to account for the agreement with 2µogs and to explore the onset of spin-rotation effects in the spectra as the magnetic field is increased. Copyright 1998 Academic Press.

Methyl Chloride nu5 Region Lineshape Parameters and Rotational Constants for the nu2, nu5, and 2nu3 Vibrational Bands.

Fourier spectra of methyl chloride have been obtained at ambient laboratory temperature under self-broadening conditions. Five thousand two hundred and sixty rovibrational transitions of the (nu2, nu5, 2nu3)-vibrational-band triad have been assigned, and new ground and excited state rotational constants for CH335Cl and CH327Cl have been determined. The nu5 and nu2 vibrational-band intensities are determined to be, respectively, 42(1.2) and 31.7(0.9) cm-2 atm-1. Self-broadening coefficients of individual rovibrational lines are determined for the nu5 band of CH335Cl and CH337Cl at 296 K. The self-broadening coefficients peak broadly close to the maximum in the Boltzmann rotational population; no specific trends of the broadening coefficients are observed with the rotational quantum number K. With the exception of the RQ(J, 0) branch, the 1260-1650 cm-1 spectral region can be well modeled by the superposition of overlapping Voigt line profiles. To adequately model the densely packed RQ(J, 0) branch, however, we included collisional line mixing with A+ to A- in addition to A- to A- and A+ to A+ |DeltaJ| >/= 1, DeltaK = 0 collisional transitions allowed. Copyright 1998 Academic Press.

Prognosis for a mid-infrared magnetic rotation spectrometer for the in situ detection of atmospheric free radicals.

Mid-infrared magnetic rotation spectroscopy (MRS) experiments on nitric oxide (NO) are quantitatively modeled by theoretical calculations. The verified theory is used to specify an instrument that can make in situ measurements on NO and NO(2) in the Earth's atmosphere at a sensitivity level of a few parts in 10(12) by volume per second. The prototype instrument used in the experiments has an extrapolated detection limit for NO of 30 parts in 10(9) for a 1-s integration time over a 12-cm path length. The detection limit is an extrapolation of experimental results to a signal-to-noise ratio of one, where the noise is considered to be one-half the peak-to-peak baseline noise. Also discussed are the various factors that can limit the sensitivity of a MRS spectrometer that uses liquid-nitrogen-cooled lead-salt diode lasers and photovoltaic detectors.

Integrated band intensities of gaseous N(2)O(5).

Values for mid-IR integrated band intensities of gaseous N(2)O(5) were determined at room temperature. The absorptions studied were at 1720, 1246, 743, and 557 cm(-1). The integrated intensities were 2204, 581, 685, and 699 atm(-1)-cm(-2), respectively. Implications of these results for the stratospheric detection of N(2)O(5) are discussed.

Measurement of weak ir absorption with a tunable laser: the hydrogen S(2)(1) line strength.

A tunable laser light source has been used to obtain the intensity of the S(2)(1) hydrogen quadrupole line at ~8604.2 cm(-1). The result (0.0140 +/- 0.0007 cm(-1)/km-amagat) is in excellent agreement with a previous determination as well as with ab initio calculations.