H2 line-mixing coefficients in the ν2 and ν4 bands of PH3 at low temperature

- The spectra have been recorded with a tunable diode-laser spectrometer at 173.2 K.
- The line-mixing coefficients are determined by a multi-pressure fitting procedure.
- The effect of the line-mixing in the spectra, appear to be important.

Using a tunable diode-laser spectrometer adapted with a low temperature cell, we have measured the H2 line-mixing coefficients for 21 lines in the QR branch of the ν2 band and in the PP and RP branches of the ν4 band of phosphine (PH3) at low temperature. These coefficients were determined using a multi-pressure fitting procedure that accounts for the apparatus function, the Doppler and the collisional effects. These lines with J values ranging from 2 to 11 and K from 0 to 9 are located in the spectral range from 1016 to 1093 cm−1. The variations of these parameters with the temperature, and the ro-vibrational quantum numbers are discussed.

Comparisons of the determined line-mixing coefficients (in atm−1) obtained in this study in the ν2 and ν4 bands of PH3 at T=173.2 K with those measured at T=298 K for different values of the J quantum number.82