Yoshito Amako

The electronic spectrum of the tropone molecule

Abstract From both theoretical and experimental examination of the first absorption band of the tropone spectrum, it is concluded that the band is composed of two electronic π→π* transitions having parallel and perpendicular polarizations with respect to the symmetry axis of the molecule; this is in complete agreement with the results of Weltin et al. The most important thing to account for such an assignment of the tropone spectrum in a theoretical manner is to consider the bond alternate characters.

Permanent electric dipole moment and polarizability in Stark modulation spectra of the ICl B–X transition

Because the induced dipole moment due to polarizability in a moderate electric field is thought to be small, the Stark effect due to polarizability has generally been ignored for molecules that have a permanent electric dipole moment. However, by observation of the Stark modulation spectra (SMS), we have confirmed that the effects of polarizability and of the permanent dipole moment are sometimes comparable. Based on this observation, we have sought an estimate of the polarizability. It was also found that the effect of the polarizability on the SMS depends mainly on its isotropic part. Thus, for the B–X electric transition of the ICl molecule, the differences in isotropic polarizabilities were estimated to be Δᾱ=3.4–3.8 A3 at the 3–1 transition, and Δᾱ=3.6–4.3 A3 at the 1–0 transition, assuming that the differences of anisotropic polarizability Δαan are within the range 2–9 A3 for both transitions. Thus, obtained values of Δᾱ were confirmed to be in a reasonable range, in spite of a wide range uncertaint...

The direction of electric dipole moment of ICl A 3Π1 state through the analysis of the Stark modulation spectroscopy

Recently, two works were reported that the permanent electric dipole moment of the ICl A state has the same direction as that of the X state, through the analysis of electric and magnetic pendular spectra and through the direct analysis of the hyperfine structures under the Stark effect, respectively. We determined clearly and sensitively the direction of the dipole moment in the A (v=27) state of I35Cl, through the line shape analysis of the Stark modulation spectra (SMS). While the result was the same as those of previous two works, the analysis of the line shape of the SMS was so useful to determine the relative direction of the dipole moment of the upper electronic state to that in the lower state, whichever of the first-order or the second-order Stark effect the state may show.

Fluctuation Spectroscopy: The Determination of Chemical Reaction Rates Based on the Optical Density Fluctuation

The analysis of the half-width of the frequency spectrum due to the concentration fluctuation around the equilibrium value should give the rate constant of a chemical reaction under the appropriate condition. Specially, in a chemical reaction among the molecular species which have respectively different light absorption coefficients, the concentration fluctuations of each component molecule induce the corresponding fluctuation of the transmitted light to be observed. The optical detection of the low level signal due to the concentration fluctuations from the transmitted light was shown to be possible with the effective elimination of the part of the shot noise in the photo current, whose power spectrum was analysed to give the reaction rate constant.

A Synchronous Wavelength Sweeping Method of a Diffraction Grating Fabry-Perot Interferometer in U.V. and Visible Regions

To expand the free spectral range of the Fabry-Perot etalon spectroscope, a synchronous wavelength sweeping method of a grating with the pressure scanning of the etalon was devised. By this method the unwanted orders of decomposed light from the etalon were eliminated and the free spectral range Δνexpanded by an order of magnitude, depending on the maximum high pressure that the chambers containing the grating and the etalon could tolerate. Moreover, the method had the advantage of being readily usable at any desired wavelength in the U.V. and visible regions.