Collision broadening of CO2 transitions in the region of 4.3 µm. Effects of broadening gas (He, Ar and N2), rovibrational states and temperature

Abstract

The collision-broadening parameters, b⁰_L, for a number of lines in the Δν₃= 1 transitions from the (00⁰0), (01¹0), (02⁰0) and (02²0) vibrational states of ¹²C¹⁶O₂ and the (00⁰0) state of ¹⁸O¹²C¹⁶O have been measured at room temperature (300K) and with N₂, Ar and He as the broadening gases, using a tunable IR diode laser. The values of b⁰_L decrease with increase in the rotational quantum numbers associated with the transition but there is no significant difference in the broadening of lines from different vibrational bands. Measurements of b⁰_L were also carried out at 160 K on lines in the (00⁰1,00⁰0) band. With the changes in b⁰_L(units of cm^–1 atm^–1) expressed in the form b⁰_L(T)=b⁰_L(T= 298 K)(298/T)ⁿ, n= 0.69 ± 0.17 for He, 0.88 ± 0.18 for Ar, and 0.85 ± 0.09 for N₂.