Diode laser spectroscopy of methyl iodide at 850 nm

Using the Tunable Diode Laser Absorption Spectroscopy (TDLAS) 82 CH$_3$I ro-vibrational overtone absorption were detected for the first time between 11660 and 11840 cm$^{-1}$ (844 -- 857 nm), with strengths estimated to be around $10^{-27}$ -- 10$^{-26}$ cm/molecule. The lines have been measured utilizing commercial heterostructure F-P type diode lasers, multipass cells and the wavelength modulation spectroscopy with second harmonic detection technique. A high modulation amplitude approach was adopted for the analysis of the line shapes. Self-broadening coefficients have been obtained for two lines.