[Research on high resolution spectrum measurements of methane at 1.65 microm].

The high resolution spectrum of methane was obtained around 1.65 microm using a tunable DFB diode laser with a long adjustable optical path white * cell (46.36-1 158.90 m) at room temperature through the direct absorption technique. The typical line width of the DFB diode laser is about 10 MHz and the wavelength of DFB laser was calibrated by an optical wavemeter. A total of 259 new absorption lines were studied from 6 043.00 to 6 053.72 cm(-1) at five different pressures and optical lengths. All the data were fitted by Gaussian profile, the line intensities, positions and the percent of the statistical standard deviation (sigmaS/ S) % of the line intensities were obtained, and the absorption lines which are hard to be distinguished were analyzed in this paper. The weakest absorption line is 4.3 x 10(-27) cm(-1) x (mol x cm(-2))(-1), while the lines stronger than 3.0 x 10(-24) cm(-1) x (mol x cm(-2))(-1) were ignored for their saturated absorption due to the long absorption optical length(788-1 000 m). Meantime, the spectrum shows the abundance of methane weak lines and its extremely complex structure around 1.65 microm. All the lines cannot be found in HITRAN2004 database, and as to our knowledge, they were not reported before by other papers.