Michio Okuda

Spectroscopy of the CH3O A 2A1–X 2E system by laser‐excited fluorescence method

Laser‐excitation spectra and single vibronic level fluorescence spectra of CH3O and CD3O A 2A1–X 2E transitions are reported. The spectral origin of the excitation spectrum is at 31 540 cm−1 (317.06 nm); extensive progressions in the stretching mode ν3′ (678 cm−1 for CH3O and 655 cm−1 for CD3O) dominate the spectra. Fluorescence bands appear that are assigned as the transition to the C–O stretching mode and CH3 deformation modes, giving ν3″=1015 cm−1 for CH3O and 1010 cm−1 for CD3O. Measured vibronic band intensities agree well with the Franck–Condon calculation. The band shape is well reconstructed on the assumption of SCF calculated geometry. No predissociation occurs below 35 900 cm−1.

Geometrical form factor in the laser radar equation: an experimental determination.

This paper describes a practical method for determination of the geometrical form factor in the laser radar equation. Based on the laser radar equation and the statistical homogeneity in the spatial aerosol distribution, the factor can be calculated from the field observations by laser radar. Some examples of correction by this factor are also presented.

Laser‐induced fluorescence of the C2H5O radical

Laser‐excitation and laser‐induced fluorescence spectra of the C2H5O radical are reported. The 0–0 band of the ?–? transition lies at 29 204 cm−1 (342.4 nm). The spectra are characterized by a prominent progression involving the C–O stretching mode, as in the case of the CH3O radical. The fundamental C–O stretching frequencies in the ground and excited states are 1067 and 596 cm−1, respectively.

The emission of CH3O from the reactions of metastable rare gas atoms with methanol

The uv emission spectra of CH3O (2A1→X2E) observed in the reactions of metastable rare gas atoms (Ar and Kr) with methanol are reported.(AIP)

Emission of NO2* formed in the photodissociation of N2O4

Visible emission was observed when the equilibrium mixture of NO2 and N2O4 was irradiated with near‐UV laser light. The excitation spectrum from 295 nm to 365 nm resembles the absorption profile of N2O4, and the intensity is proportional to the number density of N2O4. This emission was ascribed to NO2* formed in the photodissociation of N2O4; N2O4+hν→NO2*+NO2. The quantum yield of this process is of the order of unity, and the fluorescence yield of direct excitation of NO2 in this wavelength range is less than 10−4.

Observation of 3-Hexene-2,5-dione in the Photooxidation of 1,2,4-Trimethylbenzene in the NO-H2 O-Air System

Abstract Formation of 3-hexene-2,5-dione (diacetylethylene) was observed in the photooxidation of 1,2,4-trimethylbenzene in the mixture of NO-H2O-air. The 3-hexene-2,5-dione is a larger aromatic ring-ruptured compound than has been reported. Although the yield of 3-hexene-2,5-dione collected was very low, the formation of 3-hexene-2,5-dione showed that the formation of other large dicarbonyl compounds due to the cleavage reaction of aromatic ring is possible in the photooxidation of aromatic hydrocarbons. Formation of 3-hexene-2,5-dione was also observed in the photooxidation of the p-xylene system.

O2* (a 1Δg) in the reaction of H+O3

The reaction of atomic hydrogen with ozone is studied in order to clarify whether O2(aΔg) is formed in the reaction. A photoionization mass spectrometer compiled to a fast flow reaction was used.(AIP).

A mobile computerized laser radar system for observing rapidly varying meteorological phenomena

A high repetition, mobile laser radar system with a computerized real-time data acquisition and display system is described. Signal-to-noise levels of the system are compared with theoretical values, and it is found that they are affected by the shot noise in the system. An example of a stack plume observation is also presented to show the performance of the system.

Reaction of methyl radicals with ozone

The rate constant for the reacton of methyl radicals with ozone has been examined. The methyl radicals were generated by the reaction of oxygen atoms with ethylene in a fast flow reactor, and were detected using a photoionization mass spectrometer. For a sufficiently high concentration of oxygen atoms, the methyl radicals were observed to be at their steady state concentration. Addition of the O3–O2 mixture to this system caused a decrease in the steady state CH3 concentration, due to the reactions, CH3+O3→products (5) and CH3+O2→products (4). Signals from the CH3 radical were measured in the presence and absence of ozone. In the case of no ozone, the O3–O2 mixture was passed through a heated quartz tube to convert the ozone to molecular oxygen. Since the rate constants for the reaction of CH3+O and CH3+O2 were determined previously, the absolute rate constant for reaction (5) could be obtained from the competition among these reactions. The rate constant determined for reaction (5) is (7.0±2.7)×10−13 cm3...

Detectivity estimation of the DAS lidar for NO 2

The detectivity of an NO(2) spatial distribution by a DAS lidar was estimated under practical conditions, and its capability was clarified.