Measurements of collision-broadened line widths in the v4-fundamental band of 12CH4 at low temperatures

Temperature dependence of rotational relaxation of methane in the 2ν3 vibrational state by self- and nitrogen-collisions and comparison with line broadening measurements

“…Using the temperature exponent given in Ref. [17], N 2 -broadening coefficients of 0.133 (E-symmetry) and 0.152 cm À1 atm À1 (F-symmetry) are obtained at 100 K. These values are not very different from our measurements but the broadening coefficient was found larger for the F-symmetry than for E-symmetry contrary to the present results. In a smaller temperature range, 161-295 K, the same authors [18] measured the N 2 -broadening coefficient of the R(4)A 1 and R(4)E lines, leading to extrapolated values at 100 K of 0.141 and 0.122 cm À1 atm À1 , respectively.…”

“…For N 2 -broadening, apart from the measurements performed at low temperature for unassigned lines of the 0.619 and 0.682 lm bands [15] or of the 0.727 lm band [16], most of the other temperature-dependence studies relate to the m 4 band [17][18][19][20] but there are no data at temperature lower than 130 K [17]. At this temperature, the lowest J value of m 4 levels in the studied lines is J = 4 that is the upper level of the P(5)E and P(5)F lines.…”

“…The collisional broadening coefficients have been measured for various CH 4 transitions as a function of temperature for self-or N 2 -broadening [13][14][15][16][17][18][19][20][21]. Most of the data on IR lines have been plotted in Figs.…”

N2-, O2- and air-broadened half-widths and line shifts for transitions in the ν3 band of methane in the 2726- to 3200-cm−1 spectral region

“…There have been numerous half-width measurements for transitions of 12 CH 4 with N 2 [24,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]] O 2 , [32,42,44,45,48,49] air [32,36,38,40,42,43,45,[50][51][52][53], CH 4 [32,34,36,39,44,48,49,[54][55][56][57][58][59][60], and other molecules/atoms [32,…”

The effect of water vapour broadening on methane eddy correlation flux measurements

“…The total error for our broadening coefficients is estimated to + 2-4% (see text) 7r% very good agreement is found with Rinsland results for lines 1 and 3, while the difference for line 2 is somewhat higher and unexplained. For hydrogen and helium differences with the results of Varanasi and Chudamani (1989b) are higher than for air and nitrogen but still within the combined error limits. There appears to be a tendency for our broadening coefficients to be smaller compared to the other experiments listed in Table I for reasons which are not yet understood.…”