The absorption spectrum of phosphine (PH 3) between 2.8 and 3.7 μm: Line positions, intensities, and assignments

Abstract

Over 8000 line positions and intensities of phosphine (PH 3) at 3 μm have been measured at 0.0115 cm −1 resolution with the McMath-Pierce Fourier Transform spectrometer at Kitt Peak. The observed line intensities ranged from 4.13 × 10 −6 to 4.69 × 10 −2 cm −2 atm −1 at 296 K, for line positions between 2724.477 and 3601.652 cm −1. This region spans eight interacting vibrational states: 3 ν 2 (2940.8 cm −1), 2 ν 2 + ν 4 (3085.6 cm −1), ν 2 + 2 ν 4 (3214.9 cm −1), ν 1 + ν 2 (3307.6 cm −1), ν 2 + ν 3 (3310.5 cm −1), 3 ν 4 (∼3345 cm −1), ν 1 + ν 4 (3426.9 cm −1), and ν 3 + ν 4 (3432.9 cm −1). Assignments have been determined for all the bands except 3 ν 4 (a weak band in a highly congested area) for a total of 4232 transitions. The total integrated intensity for this region is 5.70 cm −2 atm −1 near 296 K, and assigned lines account for 79% of the observed absorption. The two strongest bands in the region are ν 1 + ν 4 and ν 3 + ν 4 with band strengths at 296 K of 1.61 and 2.01 cm −2 atm −1, respectively. An empirical database of PH 3 line parameters (positions, intensities, and assignments) is now available. Lower state energies (corresponding to assignments from this study) and line widths from the literature are included; default values are used for unassigned features.