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Ground and low-lying electronic states of Cr atoms in the gas phase were generated from photolysis of Cr(CO) 6 vapor in He or Ar using an unfocussed weak UV laser pulse and their reactions with O 2 and N2O were studied. When 0.5-1.0 Torr of Cr(CO)6 /O2 /He or Ar mixtures were photolyzed using 295-300 nm laser pulses, broadband chemiluminescence peaked at ~420 and ~500 nm, respectively, was observed in addition to the atomic emissions from z 7 P o , z 5 P o , and y 7 P o states of Cr atoms. When N2O was used instead of O2, no chemiluminescence was observed. The chemiluminescence intensities as well as the LIF intensities for those three low-lying electronic states (a 7 S3, a 5 S2 and a 5 DJ) showed second-order dependence on the photolysis laser power. Also, the chemiluminescence intensities were first-order in O 2 pressure, but the presence of excess Ar showed a strong inhibition effect on them. Based on the experimental results, the chemiluminecent species in this work is attributed to CrO 2* generated from hot ground state Cr atoms with O 2. The apparent radiative lifetimes of the chemiluminescent species and collisional quenching rate constants by O 2 and Ar also were investigated.

Vibronic relaxation among the Clements bands of SO2 molecule has been studied from time-resolved fluorescence spectra in the 300−350 nm region. The K‘ = 6, J‘ = 7 level of the Clements E-band was populated at 32 812.8 cm-1, and detailed time-resolved fluorescence spectra for the period 0−160 ns were obtained. Following the fast decay of the laser excited level, weak emissions from Clements A−F bands appeared almost simultaneously. The simultaneous appearance of many Clements bands was attributed to fast rovibronic relaxation of the laser excited molecules among the dark levels. It was also found that the broad apparent continuum emission following the direct fluorescence showed different decay rates at different wavelengths, but the decay rates of the emissions for λ > 350 nm were virtually identical. Based on the wavelength dependence of the decay rates, the apparent continuum emissions were ascribed to the emissions from the rovibronically dispersed hybrid bright states and the low-lying rovibrational l...

Collisional quenching of Ga(5p) atoms by H 2 , D 2 and CH 4 has been studied. The gallium atoms were generated by photolysis of trimethyl gallium using a KrF laser. The Ga(5p) state was populated by two-photon excitation from the ground state and cascade fluorescence from Ga(5s) atoms was analyzed to extract quenching rate constants for Ga(5p) atoms. The apparent quenching rate constants for Ga(5p) atoms are (4.6±0.3)×10 −10 , (3.4±0.3)×10 −10 and (7.8±0.2)×10 −11 cm 3 molecule −1 s −1 by H 2 , D 2 and CH 4 , respectively. It is found that the predominant process for the large quenching rate constants for Ga(5p) atoms by H 2 and D 2 is the energy transfer for Ga(5s) formation.

Relative formation efficiencies of the ground state Fe atoms from two-photon dissociation of Fe(CO)5 have been studied using an unfocused weak laser pulse at 386.0, 368.0, 319.3 and 298.4 nm. The laser wavelengths correspond to a5D4 → z5D4, a5D4 → z5F4, a5D4 → z3F4 and a5D4 → y5D3 transition frequencies of an Fe atom. The relative amounts of Fe atoms generated by two-photon dissociation of Fe(CO)5 were obtained by comparing the emission intensities from the excited state of Fe atoms with and without a pulsed dc discharge. The relative formation efficiencies are 100:21:0.2:0.08 as the photon energy decreased.

We have systematically measured the noise power spectral density ( S υ ( f )) of the YBCO micro-bridge as a function of frequency, temperature and magnetic field. In all the cases above, S υ ( f ) shows V 2 / f α behaviour at the measured frequency range of 0.2 f V , the d.c. voltage across the sample and, α the fitting parameter to be determined. In the normal state, the normalized noise power spectral density ( S n ( f ) = S υ ( f )/ V 2 ) is four or five orders of magnitude larger than that of the normal metals evaluated by Hooge's formula or thermal fluctuation model. Near the zero resistance temperature ( T c 0 , S n ( f ) was found to further increase by eight orders of magnitude and α was shown to increase from 1 to 2 depending on the frequency range. Furthermore, once a magnetic field is applied, S n ( f ) showed a marked increase near T c O . This anomaly is attributed to magnetoic vortices coupled with the enhanced instability of space-time coherence associated with Cooper pair as a result of applied magnetic field.

In situ high‐Tc superconducting thin films of YBa2Cu3O7−x were deposited on (100) SrTiO3 substrate by laser ablation with a glancing angle geometry at different substrate temperatures in the 560–700 °C range. The transition temperatures, x‐ray diffraction patterns, and surface morphologies of the films were substantially different from one another. The critical temperatures of the films deposited at below 600 °C were 72–84 K, while the films deposited at above 650 °C showed Tc0 of 85–91 K. The x‐ray diffraction patterns and surface morphologies of the films showed that the orientations of the deposited films depended on the substrate temperature. The films deposited at 700 °C showed an exclusive orientation of ‘‘c’’ axis perpendicular to the (100) SrTiO3 substrate surface, but those deposited at below 600 °C exhibited random but a preferential orientation of c axis parallel to the (100) SrTiO3 surface. The dependence of the film orientations versus substrate temperature is explained in terms of lattice mi...

We have fabricated three-dimensional (3D) photonic quantum ring lasers with an equilateral triangle microcavity. Their spectra were well explained by combining the off-normal resonance and hexagonally bounced in-plane whispering-gallery-mode condition. The angular distribution of the emission modes and their discrete wavelengths were shown to be in excellent agreement with a 3D Rayleigh Fabry-Perot model. We confirmed that the allowed modes in the equilateral triangle microcavity decrease by decreasing the length of equilateral triangle side, L, and the spectral mode spacing linearly increases with the mode index m and is inversely proportional to L2.

We report on a new, simple, effective and fast cell sorting method for massive micro-manipulation of biological cells or small particles in microfluidic channel involving a sorter-on-mega photonic quantum ring (PQR) hole laser chip scheme.

The measurement of the normalized noise power spectral density (Sn(f)=Sv(f)/V2) of the YBCO microbridge sows 1/falpha dependence. The key features of the present measurements are as follows: in the normal state, Sn(f) is several orders of magnitude larger than the value predicted by Hooge (1969); near Tc, Sn(f) increases by several orders of magnitude and alpha approaches 2; the noise power increases in a magnetic field near Tc. This enhancement of Sn(f) seems to be related to fluctuation at the phase transition due to the instability of Cooper pair formation and breaking.