National Institute Of Materials Physics - Romania
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articles found
841. On the photoluminescence decay in porous silicon films
Authors:
Baltog, I; Ciurea, ML; Pavelescu, G; Mihut, L; Baibarac, M
Published: 1998, FIFTH CONFERENCE ON OPTICS (ROMOPTO '97), PTS 1 AND 2, 3405, 626, DOI: 10.1117/12.312818
The photoluminescence (PL) decay measurements were performed on porous silicon films. It was observed that the two components of FL, one of them fast (ns) and the other slow (mu s or ms sometimes) have different contributions to PL signal, depending on the wavelength of the excitation light. The slow component of PL was in details investigated. Time decay cures for different excitation (337.1 nm, 470 nm and 550nm) and emission (550, 650, 700, 800 and 860 nm) wavelengths and also for different excitation intensities were taken. All decay curves were fitted with a stretched exponential. The slow component of PL was proposed to be attributed to the radiative recombination on surfaces.
842. Radiation effects on polyoctenamer
Authors:
Chipara, MI; Georgescu, L; Oproiu, C; Chipara, MD; Niculescu, A; Galatanu, N; Reyes, JR; Secu, CE
Published: AUG 1997, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 131, 191, DOI: 10.1016/S0168-583X(97)00339-X
The effect of electron beams on polyoctenamer is investigated by viscosimetry, swelling and electron spin resonance spectroscopy. From these experimental investigations it has been deduced that the main degradation process in polyoctenamer is its crosslinking during electron beam irradiation in air, at room temperature. (C) 1997 Elsevier Science B.V.
843. Thermal stability of amorphous Se/CdSe multilayers
Authors:
Popescu, M; Sava, F; Lorinczi, A; Vateva, E; Nesheva, D; Koch, PJ; Gutberlet, T; Uebach, W; Bradaczek, H
Published: AUG 1997, SOLID STATE COMMUNICATIONS, 103, 434, DOI: 10.1016/S0038-1098(97)00207-X
The thermal stability of amorphous Se/CdSe multilayers has been investigated by X-ray diffraction. The multilayer structure is stable up to similar to 60 degrees C. After annealing at higher temperatures hexagonal selenium and hexagonal CdSe phases with nanometric crystallite size were revealed. (C) 1997 Elsevier Science Ltd.
844. Impurity-V-K centres' associations in KI crystals containing lighter halogens
Authors:
Matei, L; Serban, T; Secu, M; Beica, T
Published: JUN 1997, JOURNAL OF LUMINESCENCE, 72-4, 692, DOI: 10.1016/S0022-2313(97)00039-2
An attempt has been made to put in evidence the modified V-K centres in low temperature UV irradiated Kl:Cl crystals. The interpretation of the results seems to favour a new type of V-K centre localised near an impurity halogen instead of a heteronuclear V-K centre.
845. Structure and hardness modifications induced by UV light in Ge-As-S amorphous chalcogenide films
Authors:
Popescu, M; Skordeva, E; Arsova, D; Vateva, E; Sava, F; Lorinczi, A
Published: 1997, CAS '97 PROCEEDINGS - 1997 INTERNATIONAL SEMICONDUCTOR CONFERENCE, 20TH EDITION, VOLS 1 AND 2, 470, DOI:
X-ray diffraction and transmission experiments as well as hardness measurements on virgin and ultra violet (UV)-irradiated amorphous films in the system GexAs40-xS60 have been performed. The W-light determines the plm softening for x<19 and film hardening for x>19. The structure remains amorphous but the distance characteristic to medium range order (MRO) shows variations as a function of composition and irradiation time. The main effect of the UV light is the release of a significant amount of sulphur.
847. A comparative study of zinc-polyaniline electrochemical cells having sulfate and chloride electrolytes
Authors:
Sima, M; Visan, T; Buda, M
Published: AUG 1995, JOURNAL OF POWER SOURCES, 56, 136, DOI: 10.1016/0378-7753(95)80024-B
Polyaniline (PANI) films were investigated at 20 degrees C as the positive electrodes for Zn/PANI secondary cells containing either 1 M ZnCl2, 0.5 M NH4Cl or 1 M ZnSO4, 0.18 M (NH4)(2)SO4 electrolytes, respectively, at pH=4.5, Cyclic voltammograms showed similar behaviour for the thin PANI films as those in highly acid media. From the discharge curves specific capacities were calculated of 127-130 Ah kg(-1) for the Zn/PANI, Cl- cell and 82-107 Ah kg(-1) for the Zn/PANI, SO42- cell. Charging limit values of 1.48 V for the Zn/PANI, Cl- cell and 1.52 V for the Zn/PANI SO42- cell were obtained in order to prevent the electrochemical inactivation of the polymer. After 20 to 30 cycles the capacity of both cells decreases rapidly and then levels off. The self-discharge process is important only in the first approximately 80 h, after which the open-circuit voltage remains constant. Zn/PANI, Cl- cell showed better electrical characteristics for use as a secondary system.
848. INFLUENCE OF INITIAL CONDITIONS ON THE OPTICAL AND ELECTRICAL CHARACTERIZATION OF SILLENITE-TYPE CRYSTALS
Authors:
HAMRI, A; SECU, M; TOPA, V; BRIAT, B
Published: JAN 1995, OPTICAL MATERIALS, 4, 201, DOI: 10.1016/0925-3467(94)00101-4
We compare a set of results concerning our measurement of the optical absorption (OA), photoconductivity (PC), thermally stimulated currents (TSC) and thermally stimulated luminescence (TSL) on the same crystal. We also investigate the effects of various preillumination treatments at room or liquid nitrogen temperature. We conclude that illumination with infrared light (rather than solely red) plays an important role which has been underestimated in the past.
850. PLASMA-TARGET COUPLING IN THE CASE OF TEA-CO2 LASER-PRODUCED BREAKDOWN IN FRONT OF A SOLID TARGET
Authors:
URSU, I; APOSTOL, I; DINESCU, M; MIHAILESCU, IN; MOLDOVAN, M; PROKHOROV, AM; AGEEV, VP; KONOV, VI; SILENOK, AV; CHAPLIEV, MI
Published: 1980, OPTICS COMMUNICATIONS, 35, 99, DOI: 10.1016/0030-4018(80)90367-3
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