Spectroscopy of ammonia in the range 6626–6805 cm⁻¹: using temperature dependence towards a complete list of lower state energy transitions

Abstract

Systematic analysis of the temperature dependence of the intensity ratio between already assigned and unassigned transitions enabled the determination of the most probable energy of the lower state of the unassigned transition. Such a procedure has been applied to transitions of ¹⁴NH₃ ammonia in the range 6626–6805 cm⁻¹ between 130 and 300 K. This information is of great interest in the considerable task of the assignment of the complete 1.5 μm infrared spectral range where combination and overtone vibrational bands are present. 2451 transitions have been observed at different temperatures. For 2133 the line strength and for 1956 transitions the values of lower state energies were derived. Our work was compared with recent Fourier transform study covering a larger energy range (6300–7000 cm⁻¹) with smaller temperature range (185–296 K)

Keywords:

• laser spectroscopy
• ammonia
• high resolution
• infrared

Acknowledgements

This work is supported by the French National Research Agency (Project ANR GASOSPIN number 09-BLAN-0066-01), by the GDRI HighResMIR (high resolution microwave, infrared and Raman molecular spectroscopy for atmospheric, planetological and astrophysical applications), by the joint Slovak-French project (SK-FR-2013-0037) and by the Scientific Grant Agency of Slovak Republic (project number 1/0918/14).