Rotational relaxation rates for theJ= 0–1 transition of N₂O by self-collisions and foreign gas collisions

Abstract

Time domain techniques using pulse methods in microwave spectroscopy have been employed to determine the population and coherence decay rates, l / T~ and l/T2, for the J = 0-1 rotational transition of ~sNzO. The pressure dependence of both relaxation rates has been investigated for the pure gas. Pressure broadening of the line (,-, l/Tz) has also been studied for mixtures with 02, N2, air and the rare gases He, Ne, Ar, Kr and Xe. The observed transient emission signals were analysed by the standard model of constant coherence decay rates and also assuming dependence of the rates on the speed of the absorber molecules. The experimental results are compared with predictions from theoretical treatments of the binary collisions.

Buffer-gas pressure broadening for the (0003)←(0000) band of N2O measured with continuous-wave cavity ring-down spectroscopy

“…4 along with the literature values for the m 3 and 2m 3 bands [4,6], and the pure rotational transitions [9][10][11][12][13][14]. Our results of the N 2 -and O 2 -broadening coefficients obtained for the 3m 3 band are in good agreement with the most of the literature values listed above.…”

“…The values of c decrease with jmj: a trend observed by our previous measurement and other groups conducting broadening measurements [3][4][5][6][7][8][9][10][11][12][13][14]22]. Based on the impact approximation, c is expressed from the cross-sections in the terms of the Weiskopf radius, the number density of the collision partner, and the mean relative velocity of the collision partner [29].…”

“…Parkes et al [8] reported for the 3m 3 band at 1.5 lm at room temperature. In addition, several measurements have also been performed for the pure rotational transitions of N 2 O in the J = 1-0 [9], 6-5 [10], 9-8 [11], 20-19, 24-23 [12], 22-21, 23-22 [13], , and 26-25 [14] transitions. In the present study, we have measured the pressure broadening coefficients in the 3m 3 band (1.52-1.53 lm) with various buffer gases (N 2 , O 2 , He, Ar, Ne, Kr and Xe) as a function of the rotational quantum number, and their temperature dependence (broadening exponent) with cavity ring-down spectroscopy (CRDS) using a tunable diode laser.…”

Temperature Dependence of N2-Relaxation of Rotational Lines of Propionitrile

“…This feature is particularly pronounced for a large ratio of the masses of perturbing and active gas molecules [15]. Although this effect has been observed previouly [16,17], it could be neglected in the case of the present study since the molecular mass of the buffer gas (N 2 ) is half the active gas one. Thus an exponential damping law was used for data analysis (after correcting for Doppler dephasing) and the corresponding rate constant (1/T 2 ) was deduced by least squares fitting of the time domain signal.…”

Centrifugal Distortion Analysis and Study of T 2 -Relaxation for l-Type Doublet Transitions of Nitrous Oxide ( 15N2O) by a Microwave Pulse Technique

“…Such a speed dependence of the rotational relaxation for the J = 0-+1 transition of N 2 0 was described in [7] and [8]. For the investigated /-type doublet transitions no significant speed dependence of the rotational relaxation rates was observed.…”