G. Mondio

Optical properties of the layer compound GaTe

Abstract The optical constants of layer compound GaTe have been obtained in the energy range 1.0 to 6.0 eV from near normal incidence reflectivity spectrum. Data have been processed to yield the real and imaginary parts of the refraction index and of the dielectric constant. Band parameters have been also empirically estimated.

Optical properties of the layered semiconductor ZnIn2S4

Abstract The wavelength modulated reflectivity spectrum of ZnIn 2 S 4 in the range 1.5–8.0 eV is presented. The first absorption onset near 3.0 eV has been related to transitions from sulphur p-like and cation s-like valence bands to a sulphur first group p-like conduction band. Evidence was also found for the existence of two M 1 -type singularities above 5.0 eV.

Valence band density-of-states in 7,7′,8,8′ tetracyanoquinodimethane

Abstract XPS measurements have been performed on the organic semiconductor TCNQ in order to have a measure of the valence band density of states. A quite satisfactory agreement has been found between the experiment and the theoretical results obtained by means of a CNDO calculation. The high-lying π-orbitals of TCNQ have been assigned to a set of hybridized molecular states of carbon (mainly) and nitrogen p -like atomic character.

Experimental evidence of a short-lived component in the fluorescent decay of the indole

SummaryIn this paper we report measurements of fluorescence phase-shift and modulation data of pure indole over a wide range of modulation frequencies. Our results firstly show two decay times in several solutions, independently of the solvent polarity. The two lifetimes are found to be of the same order of those observed in the tryptophan, with a contribution to total fluorescence of the short-lived component ranging between 4 and 6%. A brief description of the multifrequency phase and modulation fluorimetry is also given.RiassuntoIn questo lavoro vengono presentate misure di fluorescenza e di tempi di vita su soluzioni di indolo puro ottenute con la tecnica della fluorimetria di fase. I nostri risultati mostrano in modo inequivocabile due tempi di decadimento dell’indolo in soluzione indipendentemente dalla polarità del solvente. I due tempi di vita sono dello stesso ordine di quelli osservati nel triptofano, con un contributo della componente a più breve tempo di vita variabile fra il 4 ed il 6%. Viene data anche una breve descrizione della tecnica della fluorimetria di fase a multifrequenza.РезюмеВ этой статье приводятся результаты измерений сдвига фазы флуоресценции и модуляции для чистого индола в широкой области частот модуляции. Наши результаты обнаруживают два характерных времени распада в различных растворах, независимо от полярности растворителя. Отмечается, что обнаруженные два времени жизни по порядку величины совпадают с временами жизни, обнаруженными в триптофане. Вклад в полную флуоресценцию для короткоживущей компонент лежит в области от 4 до 6%. Также приводится описание многочастной фазыи флуориметрии модуляции.

Osćillator strength increase of the B-band in KBr:Tl under the thermal perturbation

Abstract The temperature induced variation of the B-band integrated absorption intensity has been determined at room temperature by a modulation technique and reported for KBr:Tl.

Lineshape of derivative reflectivity near the fundamental edge of GaTe

Abstract Wavelength-modulated reflectivity measurements have been made on GaTe single crystals in the exciton absorption region in the neighbourhood of the band gap. Lineshapes of Δϵ2, the oscillator strength and the exciton binding energy have been evaluated.

High resolution spectroscopy of the A-band absorption structure☆

Abstract Experimental evidence on the triplet structure of the A absorption band in KBr: T1 is given. The results are obtained by means of the high resolution derivative technique that allowed us to reveal the true structure of the band without applying any external perturbation to further remove the degeneracy of electronic levels. A computer best fit was also used to obtain the parameters of the three subbands in the normal as well as in the derivative spectrum.

A new self-consistent smoothing program

A new smoothing computer program is presented which may be of great interest for a large number of scientific fields. Due to its versality it was tested on Mössbauer and astrophysical data but it can always be used if scattered data in the measurements are present.

Change of the optical constants of Bi2Te3 single crystals

Abstract New structures in the reflectivity spectrum of Bi 2 Te 3 are found and assigned to proper critical transitions.

Luminescence properties of some differently substituted indoles

Abstract Solutions of some differently substituted indoles have been spectroscopically characterized and the experimental spectra have been interpreted on the basis of CNDO calculation.