Laser-induced fluorescence of PO-photofragments of dimethyl methylphosphonate.

The paper presents the results of calculating the absorption spectrum of a phosphorus monoxide (PO) molecule corresponding to the (=0)-(=0) transition. The efficiency of excitation of the PO molecule is estimated as a function of the spectral parameters of the laser radiation. The positions of the fluorescence bands of PO are calculated.

Two-pulse laser fragmentation/laser-induced fluorescence of nitrobenzene and nitrotoluene vapors.

This paper presents the results of an experimental study of the dynamic characteristics of the laser fragmentation/laser-induced fluorescence (LF/LIF) process in nitrobenzene and para-nitrotoluene vapors under synchronized two-pulse laser irradiation. It is shown that if the values of the time delay between the pulses of fragmentation (248.4 nm) and excitation (247.

Dynamics of the laser fragmentation/laser-induced fluorescence process in nitrobenzene vapors.

The paper presents the results of an experimental study of the dynamic characteristics of the laser fragmentation/laser-induced fluorescence (LF/LIF) effects in nitrobenzene vapors under the separate initiation of processes of photofragmentation and fluorescence of fragments by nanosecond laser pulses. It is shown that, due to the inertia of the dissociation mechanism of nitrobenzene molecules, the process of the fragments' formation continues even after letup of excitation. The highest concentration of fragments is reached in a time several times greater than the standard fragmentation pulse duration of 10 ns.

Use of a Fabry-Perot interferometer to isolate pure rotational Raman spectra of diatomic molecules.

We propose to use a Fabry-Perot interferometer (FPI) as a comb frequency filter to isolate pure rotational Raman spectra (PRRS) of nitrogen molecules. In making the FPI's free spectral range equal to the spectral spacing between the lines of nitrogen PRRS, which are practically equidistant, one obtains a device with a comb transmission function with the same period. However, to match the FPI transmission comb completely with the comb of nitrogen PRRS lines one should tune the wavelength of the radiation used to excite the PRRS of nitrogen exactly to the position of any minimum in the FPI transmission comb.

Daytime operation of a pure rotational Raman lidar by use of a Fabry-Perot interferometer.

We propose to use a Fabry-Perot interferometer (FPI) in a pure rotational Raman lidar to isolate return signals that are due to pure rotational Raman scattering from atmospheric nitrogen against the sky background. The main idea of this instrumental approach is that a FPI is applied as a frequency comb filter with the transmission peaks accurately matched to a comb of practically equidistant lines of a pure rotational Raman spectrum (PRRS) of nitrogen molecules. Thus a matched FPI transmission comb cuts out the spectrally continuous sky background light from the spectral gaps between the PRRS lines of nitrogen molecules while it is transparent to light within narrow spectral intervals about these lines.