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 0.003 cm(-1) was obtained. Rotational constants, B(υ), were used to derive equilibrium parameters B(e)'' = 0.03977725(77) cm(-1), a(e)'' = 1.1819(24)×10(-4) cm(-1), r(e)'' = 2.584386(25) Å of the X(2)Π(3/2,g) state, and B(e)' = 0.0305787(37) cm(-1), a(e)' = 1.2353(23)×10(-4) cm(-1), r(e)' = 2.94758(18) Å of the A(2)Π(3/2,u) state. Vibrational energies were used to derive ω(e)'' = 239.0397(55) cm(-1), ω(e)x(e)'' = 0.64951(87) cm(-1) of the X(2)Π(3/2,g) state and ω(e)' = 138.103(11) cm(-1), ω(e)x(e)' = 0.45027(34) cm(-1) of the A(2)Π(3/2,u) state. The A(2)Π(3/2,u) (υ(n) = 13) state was found to be rotationally perturbed by the a(4)Σ(1/2,u)(-) (υ(n) = 17) state through second-order spin-orbit coupling.

[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. Moreover, the fluorescence decay curves of the (1, 1) band and the (0, 0) band and were obtained and the fluorescence lifetimes of A 2sigma+ (v' = 1) state and the X 2pi (v" = 0) state were fitted to be (637 +/- 16) and (675 +/- 13) ns, respectively.

[Study on decomposition products of methanol in AC discharge by spectroscopy].

The intermediate decomposition products of methanol (CH3OH) in an AC discharge were diagnosticated via concentration modulation spectroscopy. Several main vibrational bands of CO Angström beta 1 sigma+ -alpha 1pi system, CH alpha 2 delta-X2pi system at 430 nm and beta 2 sigma- -X2pi at 390 nm, as well as CHO (329.82 nm), CH2O (369.8 nm), CH3O (347.8 nm) and Balmer series spectra of H atom were identified in the region between 300 and 670 nm. Furthermore, the dependences of the emission spectral intensities of the intermediate decomposition products on the discharge voltage and parent gas pressure were investigated in detail. The experiments indicated that the relative population ratio of CO (beta 1 sigma+) and H increases with increasing discharge voltage more quickly than that of CH (alpha 2 delta). Several possible reaction passages were given and discussed. Additionally, the vibrational and rotational temperatures of CH (alpha 2 delta) were determined to be about 4200 and 1100 K respectively, and the vibrational temperatures of CO (beta 1 sigma+) were determined to be about 2500 K by analyzing the intensity distribution using LIFEBASE computer program. The decomposition mechanism of methanol in the discharge plasma was discussed as well.

[Study on the emission spectra of N2 plasma jet by AC glow discharge].

N2 plasma jet was generated from a nozzle using an AC discharge at about 15 kV. The emission spectra were obtained by using the concentration modulation spectroscopic technique. The dependence of spectral signal on the discharge current was discussed. It was found that the vibrational temperature decreased first and then increased downstream from the nozzle by measuring the emission spectra from different axial positions in the jet. A phenomenological model was presented to explain the vibrational temperature variation with different axial position z. The N2+/N2 ratio varied along the axis and the property of discharge in the experimental system was studied.

[Study on concentration modulation spectra of the molecular ion beam by AC glow discharge].

An experimental apparatus using an AC discharge was developed for producing molecular ion beam. The emission spectral intensity of N2+ is stronger than that of N2, and a very high ratio of N2+ (B)/N2 (C) up to 6:1, was achieved in N2 discharge. The effects and processes of N2 discharge, and the concentration modulation spectra were studied. The vibrational temperature and rotational temperature of N2+ molecular ions beam were calculated to be 3 310 and 282 K respectively from the emission spectra.

[Study on the comet-tail system of 12C16O+ in the near-infrared region].

The molecular cation CO+ is a very important transient molecular radical, and the spectra of the ion has been investigated by numerous researchers. Optical-heterodyne-magnetic-rotation-enhanced velocity modulation spectroscopy(OH-MR-VMS) was employed to measure the comet-tail system (A2 pi(i)-X2 sigma+) of 12C16O+ molecular ion. The vibrational rotation absorption spectra wereobserved in the near-infrared region, including three bands of (0, 3), (1, 4) and (3, 6). A set of precise molecular constants for the A2 pi(i) (v' = 0, 1, 3) were determined using the least-squares fit. This experiment has further proved that OH-MR-VMS is very valuable in measuring absorption spectra of molecular ions.

[Investigation of the (6, 1) and (7, 2) bands in the A 2IIi-X 2sigma+ red system of CN radical].

The CN radical was produced by Penning AC discharge of the mixture of trace acetonitrile (36 Pa) and helium (660 Pa) and the ro-vibrational spectra were measured by optical heterodyne magnetic rotation enhanced concentration modulation spectroscopy in the range of 16 850-17 480 cm(-1). 138 lines and 118 lines were assigned to the (6, 1) and (7, 2) bands in red system A 2IIi-X 2sigma+ of CN respectively, while others were due to (8, 3) band in CN red system and C2 Swan band system. More accurate molecular constants of A 2IIi (v = 6, 7) state and perturbation parameters zeta and eta between A and X states were derived based on nonlinear least-square fitting, individually, by diagonalizing the effective Hamiltonian matrix involving the perturbation elements of two electronical states and the standard deviation of fitting was less than the experimental uncertainty 0.007 cm(-1), which implied the accuracy of our results.

[The method of wavelength calibration in high resolution absorption spectroscopy].

A new method for the calibration of wavelength in a measurement of high resolution molecular absorption spectra by referring the standard spectrum of iodine molecule is presented in this paper. Segment offset is employed in the calibration of wavelength, while the data smoothing, baseline determining and peak fitting are applied to preprocess the spectral data. A visual software is provided for automatically calibrating wavelength with a friendly style of mutual dialogue between human and computer. The software has been used to calibrate the absorption spectra of N2+ molecular ion in the visible region 16,422-17,896 cm-1, the absolute accuracy is about 0.006 cm-1.