Line intensity measurements of methane’s $$\nu _3$$ ν 3 -band using a cw-OPO

• DOI: 10.1007/s00340-014-5883-1
• Publication Date: 2014-06-19T15:32:57Z
• Authors: Marco P. Moreno; Malo Cadoret; Mohammad Jahjah; Linh Nguyen; Flavio C. Cruz; Jean-Jacques Zondy
• Keywords: HITRAN; Oscillator strength; Line (geometry); Torr; Intensity

We report on absolute line strength measurements of P(1), R(0) and R(1) singlet lines in the \(3.3\,\upmu\hbox {m}\,\nu _{3}\) (C–H stretching) band of methane \(^{12}\hbox {CH}_4\) at reference temperature \(T=296\) K. Line strength measurements are performed at low pressure \((P \le 1\hbox { Torr})\) using direct absorption spectroscopy technique based on a widely tunable continuous-wave singly resonant optical parametric oscillator. The \(1\sigma \) overall accuracy in line strength determinations ranges between 7 and 8 % mostly limited by pressure and frequency measurements. A comparison with previous reported values is made. Our results show good agreement with the HITRAN 2012 database.