Determination of Low Concentration HD through Laser Thermal Lensing Spectroscopy

Laser-induced thermal lensing spectroscopy was studied to analyze hydrogen gas which containedHD natural abundance of HD300ppm.一个infrared laser system of 1.382 μm InGaAs P类型was used to excite HD molecule with aprecise temperature control and frequency modulation of 1.4 to 110 kHz. At first，infrared spectrum of HD was measured with a single-path cell which contained HD gas of 100 to 800torr and 0.8 mm long. The R(1) branch of The 2-0 band was observed with a half width of 0.02cm D1-1 D1 at 7241.82 cm D1-1 D1，Herzberg在1950年的检测命令HD with a normaladsorption spectroscopy was 20 torr，100 times higher than that of the natural abundance of HD我们应用多种path cell of 32m in the effective path length to detect HD at the low pressureof less than 20 torr，但背景声音提供了关于the multi- rection也是high detect HD absorption. In thethermal lensing spectroscopya reference cell which was evacuated less than 0.001 torr and 0.8 m long was placed in a parallelgeometry of the sample cell contained the HD gas of 0.2 to 2 torr. Each laser beam是passed通过a pinhole of 0.1 mm in diameter and detected. a difference signal was detected for a sample0.2 torr HD with 100khz modulation这应该是我们可以确定的HD molecule of the natural abundance with thermal lensingspectroscopy。

Laser-induced thermal lensing spectroscopy was studied to analyze hydrogen gas which contained natural abundance of HD, 300ppm. An infrared laser system of 1.382 μm InGaAs P type was used to excite HD molecule with a precise temperature control and frequency modulation of 1.4 to 110 kHz. At first, infrared spectrum of HD was measured with a single-path cell which contained HD gas of 100 to 800 torr and 0.8 mm long. The R(1) branch of the 2-0 band was observed with a half width of 0.02 cmィイD1-1ィエD1 at 7241.82 cmィイD1-1ィエD1, which was the same wavelength observed by Herzberg in 1950. The detection limit of HD with a normal adsorption spectroscopy was 20 torr, which was equipment to a concentration of 100 times higher than that of the natural abundance of HD. We applied a multi-path cell of 32 m in the effective path length to detect HD at the low pressure of less than 20 torr, but background noise brought about by the multi-reflection was too high detect HD absorption. In the thermal lensing spectroscopy, a reference cell which was evacuated less than 0.001 torr and 0.8 m long was placed in a parallel geometry of the sample cell contained the HD gas of 0.2 to 2 torr. Each laser beam was passed through a pinhole of 0.1 mm in diameter and detected. A difference signal was detected for a sample of 0.2 torr HD with 100kHz modulation, and it shows that we can determine HD molecule of the natural abundance with thermal lensing spectroscopy.