Akira Misu

Electronic excited state of NO adsorbed on Cu(111): A two‐photon photoemission study

Two‐photon photoemission was observed from molecularly adsorbed NO on Cu(111) at 110 K. Excitation and photoemission were performed with a laser light of 5 ns duration in the photon energy range from 3.8 to 4.5 eV. The NO‐induced photoemission feature was found to be composed of two components: one was attributed to the sequential two‐photon photoemission from the ground state of adsorbed NO, the other to the one‐photon photoemission from the NO negative‐ion state which was formed by hot electrons in the Cu substrate. The two‐photon photoemission intensity from the ground state NO was resonantly enhanced at the photon energy of 3.98±0.05 eV. The photon energy dependence was attributed to resonance excitation to the excited state of adsorbed NO. Width of the resonance curve was 0.3 eV, suggesting that the lifetime of the excited state is around 2 fs. The negative‐ion state of adsorbed NO was 1.26±0.07 eV above the Fermi level. The energy width of the photoemission feature from the negative‐ion state was ab...

Optical Absorption Lines of Ruby in a Strong Magnetic Field

The Zeeman effect of the B and R absorption lines of ruby was observed photographically with strong pulsed magnetic fields up to 230 kOe at 77°K. This was achieved by flashing a Xe-lamp at the time when a magnetic field reached its peak. The duration of the pulsed field was made to be about 1 m sec which was much longer than that of the pulsed light, about 20 µ sec. The g -values of the excited states responsible for the B and R lines were measured and the comparison was made with those reported by other authors. For the Zeeman patterns of the R lines with magnetic fields perpendicular to the optic axis, the Paschen-Back effect was calculated and compared with the observed patterns.

Near Infrared Reflectivity of Graphite under Hydrostatic Pressure. I. Experiment

We report here the dependence on hydrostatic pressure up to 2.79 kbars of the two structures associated with the A 1 and A 2 transitions in the reflectivity spectra of graphite measured at room temperature in the photon energy range from 0.655 to 1.125 eV. By considering explicitly the effect of the trigonal warping upon the probabilities of these transitions, their spectral shapes are shown to be a step and a peak, respectively, resulting in new locations of critical points on the spectral features A 1 and A 2 which are different from those previously given by Bellodi et al. The observed shifts of these structures due to pressure provide the first direct experimental determination of the fractional change per unit pressure increment of the Slonczewski-Weiss-McClure band parameters γ 1 and γ 5 , yielding values of ∂ln γ 1 /∂ p =0.028 ±0.003 (kbar) -1 and ∂ln γ 5 /∂ p =0.055 ±0.016 (kbar) -1 .

Emissions of Ruby

Four emissions intrinsic to ruby crystals were studied. Two of them were R 1 , and R 2 lines. One of the other two emissions located at 14,980 cm -1 was ascribed to the transition from the 2 F 1 state. Another broad emission located at about 16,100 cm -1 was tentatively assigned to the emission corresponding to the U absorption band. The temperature dependences of the relative intensities of these emissions were measured. Thereby, the population in the emitting states was found to be in apparent thermal equilibrium. A comparison of the quantum yield of these emissions excited by the light in the U band with that by the light in the R lines revealed that a competing process exists against the transition from the 4 F 2 to the 2 E state. The mechanisms of the excitation of the emissions were analyzed. It was concluded that the three processes, i. e. the transition from an optically excited state to the emitting states, the achievement of the thermal equilibrium of populations in the emitting states, and ther...

Piezoreflectivity Studies on the Reflectivity Structures at about 8.6 eV in KBr

Piezoreflectivity spectra of KBr were measured by using uniaxial stresses in the photon energy region where a reflection band made up of three structures at 8.2, 8.6 and 8.9 eV is observed. From the dichroism observed under trigonal distortions, it is concluded that the structures at 8.2 and 8.9 eV are the transitions at the L point. The conclusion is different from those of Onodera et al. who have assigned the structures to the transitions at the X point. The trigonal deformation potentials of these structures at 8.2 and 8.9 eV are determined to be 0.32±0.12 eV and 0.58±0.06 eV, respectively, and tentative assignments of the initial and final states of the transitions are proposed.

Luminescence and Dichroism of F and M Centers in Potassium Chloride

In order to determine the model of the M center, the luminescence and dichroism of additively colored KCl were studied in detail. The polarization factor of luminescence due to M centers excited with polarized light in the F band are P (π/4)=-0.37 and P (0)=-0.17. The F band as well as the M band becomes dichroic by irradiating with polarized light in the M band at room temperature or in the F band at low temperature, and the same quantitative relation exists between the amounts of dichroism in the F and M band for both cases. Above results do not contradict the hypothesis that the second M band overlaps with the F band, and if this assumption is granted, it is concluded from the experiment that the symmetry type of the M center is not C 2 v but D 2 h . The oscillator strengths were found to be 0.65 and 0.53 of that of the F band. If the emission due to M centers excited with light in the F band is assumed to be caused by the resonance transfer from F to M centers, in order to explain the experimental val...

VUV and uv fluorescence lifetimes of Cl2

Abstract A spectroscopic study of Cl 2 by VUV laser-induced fluorescence is reported for the first time. The free jet excitation spectrum in the region between 79000 and 80100 cm −1 revealed the contribution of some additional band systems other than the dominant 2 1 Σ u + ←X 1 Σ g + transition system. The VUV and UV fluorescence lifetimes ranging from 15 ns down to 1 ns or less depended strongly upon the excitation wavelengths, but very little on the fluorescence wavelengths. Possible assignments of the excitation bands are discussed.

Piezoreflectance of K+ 3p Core Excitons in KBr

Effects of a uniaxial stress along the [011] direction on the K + 3 p core excitons in KBr are studied with the piezoreflectance technique. From stress dichroism, it is concluded that the core excitons located at 20.1 eV and 21.6 eV are due to the intraatomic transitions from the K + 3 p state to the 4 s state and from the same state to the 3dγ state, respectively. Trigonal deformation potentials or these core excitons are determined and compared with that of the \(\varGamma \) exciton at the absorption edge.

Direct measurement of magnetic circular dichroism and Kerr rotation spectra in vacuum ultraviolet using four‐mirror polarizer

A reflection‐type four‐mirror polarizer has been constructed and used in magnetocircular dichroism and Kerr rotation studies in the vacuum ultraviolet region. Geometrical properties and polarization characteristics were measured. The polarizer is sufficient to convert linearly polarized synchrotron radiation into circularly polarized light. Magneto‐optical measurements were performed using magnetization modulation technique, and measured magnetocircular dichroism and Kerr rotation spectra in yttrium iron garnet were shown to satisfy the Kramers–Kronig relation. It is concluded that the reflection‐type four‐mirror polarizer together with the synchrotron radiation can be used in magneto‐optical studies with high precision.

Yellow series excitons of Cu2O in megagauss magnetic fields

Experimental results are reported on the yellow series excitons of Cu 2 O in magnetic fields up to about 150 T. A diamagnetic shift of the n =2 exciton, and a Landau level type shift of the n =3 exciton are observed for the first time. The magnetic field dependence of the exciton spectra is found quantitatively consistent with previous data of the high n excitons obtained in low magnetic fields. These results are ac-counted for by a theory of a hydrogen atom in magnetic fields. It is concluded that in the yellow series excitons, only one mass-parameter governs both diamagnetic and Landau level type shifts.