Accurate determination of low state rotational quantum numbers (J < 4) from planar-jet and liquid nitrogen cell absorption spectra of methane near 1.4 micron

Abstract

An improved procedure for accurate determination of empirical lower state rotational quantum numbers from molecular absorption spectra is demonstrated for methane. We combine the high resolution absorption spectra in the 7070–7300 cm(-1) frequency range obtained in liquid nitrogen cooled cryogenic cell (T = 81 K) and in supersonic planar jet expansion (TR = 25 K).

Keywords

• lower state rotational quantum numbers
• molecular absorption spectra
• liquid nitrogen cooled cryogenic cell
• supersonic planar jet expansion