Measurement of rovibrational ΔJ = 0, 4, and 6 transitions in solid H2 together with their associated pair spectra

Abstract

Weak features in the infrared spectum of solid para-hydrogen containing a small amount of orth-hydrogen impurity were measured with high resolution (0.01–0.036 cm−1) and high sensitivity using a Fourier transform spectrometer. Effective absorption path lengths in the solid of 3.75 cm (for the range 4 000–10 000 cm−1) and 15.0 cm (for the range 5000–8000 cm−1) were used to observe the discrete zero-phonon rovibrational transitions U1←0(0), U1←0(1), and W1←0(0), for which accurate line positions and intensity parameters are given. Line positions for the associated satellite spectra for each of those transitions and for the Q1←0(0) and Q1←0(1) transitions were also determined. New features in the satellite spectra of the Q1←0(0), Q1←0(1), U1←0(0), and U1←0(1) transitions are reported. A novel ortho-hydrogen to para-hydrogen converter allowed convenient variation of the temperature for conversion. A multipass optical system external to the head of the cryostat was designed to extend the absorption path length through the hydrogen crystal.