摘要:

AbstractThe Raman scattering spectra of soft and rigid modes in TlGaSe2are investigated over a wide temperature range. The interaction between soft and rigid modes is observed from the description of the experimental spectrum within a model of interacting harmonic oscillators. Temperature dependences of the soft mode frequency and halfwidth are confirmed. The splitting of the rigid Raman mode in the ferroelectric phase is also detected.

ISSN:0370-1972    

DOI:10.1002/pssb.2221510138

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractTwo‐photon absorption of BGO is observed between 4.8 and 5.7 eV. The results confirm and extend previous investigations on two‐photon excited luminescence. In particular the two‐photon spectra do not show the first three structures observed in the reflectivity measurements. Therefore these structures should be assigned to excitonic transitions and to Bi3+ion transitions that are parity forbidden in two‐photon spectroscopy. In the region just above the onset, the two‐photon absorption coefficient increases with the photon energy in reasonably good agreement with the theory. Above 5 eV it increases more rapidly than predicted by the present theories for direct interband two‐photon

ISSN:0370-1972    

DOI:10.1002/pssb.2221510139

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractRaman scattering by phonons is measured in CdxHg1−xSe withx= 0 to 0.3 on (100), (110) and (111) surfaces near theE1+ Δ1energy gap at room temperature. From these measurements, the composition dependence of the HgSe‐like TO and LO mode frequencies is obtained. The plasmon‐LO phonon coupled modes and a cluster mode are also observed. Effective high‐frequency dielectric constants calculated by the extended Lyddane‐Sachs‐Teller relation show a discontinuity near the semimetal‐semiconductor transition point. This discontinuity is attributed to the contribution of interband terms to the dielectric function. The results obtained from the Raman measurements are compared with those from far‐infra

ISSN:0370-1972    

DOI:10.1002/pssb.2221510140

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe stretching vibration lines of SH−, SeH−, and TeH−centres in various alkali halides are split into several components by an external electric field. No similar effects are observed yet for other centres. The splitting patterns are measured with high instrumental resolution for various directions of field and light polarization. From the number of componental lines the orientations turn out to be 〈111〉 for all investigated centres. Possible reasons for the splitting are discussed. Paraelectric alignment, however, well known for the homologeous OH−centres, is n

ISSN:0370-1972    

DOI:10.1002/pssb.2221510141

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractOptical reflectivity spectra are measured for TiSi2, TaSi2, and WSi2thin films in the spectral range from 0.05 to 6 eV. The optical constants are obtained by Kramers‐Kronig analysis. The spectra are characterized by two spectral regions: the low‐energy free‐carrier response and the interband part. The spectra are discussed on the basis of presently existing band structure information and bonding trend calcula

ISSN:0370-1972    

DOI:10.1002/pssb.2221510142

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractA transfer matrix formalism is used to treat in a general way the optical response of different kind of metal superlattices. The dispersion relation of infinite and semi‐infinite superlattices and the reflectivity of semiinfinite superlattices are calculated. Spatial dispersion is included via additional boundary conditions. Each unit cell of the superlattices can be built up by an arbitrary number of layers with local and/or nonlocal dielectric functions. In the case of a spatially dispersive double layer unit cell the explicit dispersion relation is derived. The limits when one of the layers is local as well as the complete local case are shown to be include

ISSN:0370-1972    

DOI:10.1002/pssb.2221510143

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

ISSN:0370-1972    

DOI:10.1002/pssb.2221510101

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY