[Study on the Spiral-Torus Herriott Type Cell].

With the rapid development of social economy, the environmental pollution and the ecological destruction are continuously deteriorating while sudden environmental pollution incidents occur frequently. Real-time monitoring harmful gases of the air take advantages of spectroscopic techniques for concentration measurement. Multipass optical cells are -widely used in absorption spectrometry technique to improve gas detection sensitivity under the condition of weak absorption.

High-resolution observation and analysis of the I2+ A2Π(3/2,u)-X2Π(3/2,g) system.

Rotationally resolved absorption spectra of I(2)(+) were recorded in 12,065-13,062 cm(-1) region by employing optical heterodyne velocity modulation absorption spectroscopy. In total, 4054 lines were assigned to 24 bands in the A(2)Π(3/2,u)-X(2)Π(3/2,g) system spanning the vibrational levels υ'' = 1-4 and υ(n)' = 11-19. The assigned lines were globally fitted and an error of 0.

[LIF spectroscopic study of OH radical].

Hydroxyl radical molecular beam was generated by DC pulsed high voltage discharge. The rotational resolution excitation fluorescence spectra of the OH A 2sigma+ -X 2pi (1, 0) band were observed by using second harmonious output of a nanosecond dye laser (around 282 nm). The rotational temperature of the (1, 0) band was determined to be (30 +/- 1) K based on the analysis of the intensity distribution of the OH spectra.

[Difference-frequency generation in PPLN and water vapor detection in air].

The continuously tunable laser source has been realized in a periodically poled LiNO3 crystal based on difference frequency generation and quasi-phase-matching technique. The pump laser is an 1 W tunable Ti: Sapphire laser with a tunable region from 770 to 870 nm. The signal laser is an 1 W diode-pumped monolithic Nd : YAG laser.