摘要:

Different inner vibrational modes (stretching, bending and their combination) of the OH−ion perturbed by lattice defects induced by Mg2+in NaF have been put in evidence and studied by means of optical absorption spectroscopy in the 600–7200 cm−1wavenumber range, in the 9–300K temperature range, and for Mg2+molar concentration ranging between 10−4and 10−3. Electrical and mechanical anharmonicity effects have been detected for the stretching modes and analyzed in the framework of the anharmonic oscillator model for a diatomic molecule.

ISSN:1042-0150    

DOI:10.1080/10420159108224894

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

With a ring dye laser persistent spectral hole-burning was measured by fluorescence excitation spectroscopy in the zero-phonon lines of the2llg↔2llutransition in KI:S2−and of the3H4→3P0transition of a defect center with three D−ions in SrF2:Pr3+:D−and also in the zero-phonon line at 462.5 nm of a color center in neutron-irradiated and annealed α-Al2O3. In all three lines holes with a width in the order of 1 GHz could be obtained at 1.5 K with single frequency laser. With broad-band laser in KI:S2−and SrF2:Pr3+:D−spectral redistribution within the full range of inhomogeneous broadening could be observed which are explained by a photophysical model based on barrier crossing in asymmetric double-well-potentials. In the case of sapphire a photobleaching process is dominant which is effective also for nonselective excitation, and the holes are thermoresistant up to 300 K.

ISSN:1042-0150    

DOI:10.1080/10420159108224895

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Pulsed emission data and ODMR spectra of the 580 nm band provide evidence for an intermediate case exciton in pure and Cd2+-doped AgBr. This interpretation is based on the observed g-factor and the absence of a wavelength shift of the emission after pulsed excitation in pure AgBr. It is supported by the response of the ODMR spectra as the microwave modulation frequency is changed. The two central ODMR lines observed in AgBr (g = 1. 78) are assigned to transitions from the ms=±1 levels to the ms= 0 level of an intermediate case triplet exciton, which has an exchange coupling (singlet-triplet splitting) of -1. 9 ± 0. 2 cm−1.

ISSN:1042-0150    

DOI:10.1080/10420159108224896

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Irradiation of KI near 150 K with KrCl excimer laser irradiation (hv=5. 58 eV) produces V centers causing V2and V3bands. The two bands exhibit 100-type dichroism. In KI containing V centers, the 111 cm−1Raman signal attributed to I3-molecular ions is observed. Under KrCl excimer laser irradiation at low temperatures, resonance Raman scattering effects have been also studied for KI, NaI and LiI.

ISSN:1042-0150    

DOI:10.1080/10420159108224897

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The experimental values of the off-axis angle of FA(II) dipoles in KCl:Li+, RbCl:Li+and KF:Li+are in good agreement with those obtained from theoretical estimates of the off-centre displacements of the Li+ion calculated with the shell model potentials. On this basis, one can quantitatively predict the off-axis behaviour of FA(II) centres from the calculated off-centre positions of small impurity ions in alkali halides.

ISSN:1042-0150    

DOI:10.1080/10420159108224898

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The physical properties of Pb2+impurities in the perovskite-like lattice of KMgF3are very similar to those of (ns)2ions in alkali halides. The impurity inhomogeneous distribution leads to high dopant levels in the bottom region of the crystals, with a segregation coefficient equal to 0. 020. The optical features of the 336 nm emission support its attribution to luminescence of Pb2+ions from the relaxed excited B state.

ISSN:1042-0150    

DOI:10.1080/10420159108224899

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A method is described for determining the refractive index difference caused by the birefringence of orientedFA(II) centers in KCl:Li crystals. It is shown that the portion induced by the birefringence can be separated from an absorption spectrum measured through a polarizer-analyzer system. From this portion the refractive index difference can then be calculated with ease.

ISSN:1042-0150    

DOI:10.1080/10420159108224900

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159108224901

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The extinction of blue KNbO3crystals has been derived from measurements of transmission as well as diffuse reflectance. The large differences between results obtained on both ways is attributed to scattering. This is supported by additional observations. Scattering is caused by so far not identified inhomogeneities of the material.

ISSN:1042-0150    

DOI:10.1080/10420159108224902

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Optical pump-probe measurements on the F-center in RbCl, KCl and KBr show a ps ground state recovery, when a substantial number of F-aggregates is present. The observed de-excitation process becomes faster for a larger concentration of aggregate centers and is related to energy transfer from the excited state of the F-center to aggregate centers. This energy transfer occurs towards F2- and N-centers in KCl. Our results are in accordance with measurements of the quantum efficiency of the F-center luminescence and with transient absorption measurements.

ISSN:1042-0150    

DOI:10.1080/10420159108224903

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor