Absorption Bands and Luminescence of LiF Irradiated at Low Temperature

The low temperature IR stretching vibrations of difluorodisulfane (FSSF) and thiothionylfluoride (SSF2), in the solid phase and in a cyclohexane matrix, of the mixtures FSSF -SSF2, FSSF-OSF2 and SSF, -OSF2, and of solid difluorotrisulfane (FS3F) have been investigated. While SSF, forms no distinct oligomers, a dimer with absorption bands at 635 and 682 cm-1 has been detected in the case of FSSF. These differences between FSSF and SSF, are rationalized by the different S-F bond lengths. A structure of the FSSF dimer similar to that of the sulfur tetrafluoride dimer is proposed. The low temperature spectrum of FS3F shows 3 bands in the frequency range between 460 and 1000 cm-1: 590, 605 and 680 cm-1, due to associated molecules. FS3F decomposes on warming. The main decomposition products containing fluorine are FSSF and SSF2. Mechanisms for the rearrangement and decomposition of the three compounds studied are discussed

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Color Centers in Magnesium Doped Polycrystalline Alumina

MRS Proceedings ◽

10.1557/proc-667-g7.1 ◽

2001 ◽

Vol 667 ◽

Cited By ~ 6

Author(s):

L. R. Brock ◽

K. C. Mishra ◽

Madis Raukas ◽

Walter P. Lapatovich ◽

George C. Wei

Keyword(s):

Low Temperature ◽

Emission Band ◽

Emission Spectroscopy ◽

Color Centers ◽

Absorption Bands ◽

Fluorescence Excitation ◽

Polycrystalline Alumina ◽

Zero Phonon Line ◽

Related Defect ◽

Single Crystal Sapphire

ABSTRACTWe have investigated color centers in MgO-doped polycrystalline alumina (PCA) using absorption, excitation, and emission spectroscopy. Most of the color centers that were reported in earlier studies of the crystalline material have been observed to be present in the polycrystalline material. The absorption spectral features observed in the PCA are attributed to various color centers; however, they are not sufficiently resolved to make unique assignments. Suitable combinations of excitation and emission spectroscopy and also measurements at low temperature were therefore used to identify most of the color centers in this material.Among the numerous color centers that we have identified in PCA are variations of electron centers including F, F+, F2+, F22+ and F+-Mg ((Vo•-MgAl')x). The most prominent oxygen vacancy related defect observed at room temperature was the F+-Mg center, with absorption bands located at 217 and 249 nm, and an emission band at 303 nm. This center can be thought of as being formed by association of an F+ center with a Mg defect. The single crystal sapphire samples containing no Mg show only F+ (Vo•) centers with 230 and 257 nm absorption bands, and a 328 nm emission band.Low temperature (22 K) fluorescence excitation measurements of PCA led to emission from F22+center at 467 nm. Additionally, there is evidence that the observed 368 nm emission band could be attributed to the zero-phonon line associated with the F2+center.

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Low Frequency Infrared Absorption Bands of Water of Crystallization at Low Temperature

Bulletin of the Chemical Society of Japan ◽

10.1246/bcsj.44.372 ◽

1971 ◽

Vol 44 (2) ◽

pp. 372-374 ◽

Cited By ~ 7

Author(s):

Kunio Fukushima

Keyword(s):

Low Temperature ◽

Infrared Absorption ◽

Low Frequency ◽

Absorption Bands ◽

Infrared Absorption Bands

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PHOTOINDUCED PHENOMENA OF CHALCOGEN MICROCLUSTERS CONFINED IN THE ZEOLITE CAGES

Surface Review and Letters ◽

10.1142/s0218625x96001285 ◽

1996 ◽

Vol 03 (01) ◽

pp. 711-715 ◽

Cited By ~ 8

Author(s):

K. MARUYAMA ◽

T. TSUZUKI ◽

M. YAO ◽

H. ENDO

Keyword(s):

Low Temperature ◽

Band Gap ◽

Photoacoustic Spectroscopy ◽

Band Gap Energy ◽

Dangling Bonds ◽

Absorption Bands ◽

Appreciable Change ◽

Gap Energy ◽

Zeolite 4A ◽

Photoinduced Phenomena

Photoacoustic spectroscopy measurements have been carried out on the Se-ring microclusters confined in the cages of zeolite 4A. The shift of photoabsorption edge and the new absorption bands around 1.5 and 1.9 eV appeared by illumination of the light having the band-gap energy at low temperature. These phenomena may be associated with the distortion of Se ring and the formation of dangling bonds. Mixing of S or Te to the Se microclusters causes appreciable change in the photoinduced phenomena.

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Highly Sensitive Biochemical Analysis Using Low-Temperature Infrared Spectroscopy Measurements

Applied Spectroscopy ◽

10.1366/0003702971939352 ◽

1997 ◽

Vol 51 (11) ◽

pp. 1682-1686 ◽

Cited By ~ 3

Author(s):

Toshiko Fujii ◽

Yuji Miyahara ◽

Yoshio Watanabe

Keyword(s):

Aqueous Solution ◽

Infrared Spectroscopy ◽

Low Temperature ◽

Infrared Absorption ◽

Biochemical Analysis ◽

Attenuated Total Reflection ◽

Absorption Bands ◽

Creatinine Concentration ◽

Ft Ir ◽

Infrared Absorption Bands

A sensitive infrared spectroscopic analysis of biochemical components in an aqueous solution is described. The infrared spectrum of an aqueous solution containing glucose, urea, and creatinine was measured at −4.7 °C by Fourier transform infrared spectroscopy (FT-IR) with an attenuated total reflection (ATR) crystal. The infrared absorption bands of these components increased by about 100 times at −4.7 °C as compared with those measured at 22 °C. This increase in the infrared absorption bands was found to occur because of segregation of the components toward the surface of the ATR crystal caused by solidification of the sample solution. The creatinine concentration in an aqueous solution, prepared in the physiological range of human blood, was also estimated at −4.7 and 22 °C by using the partial least-squares (PLS) method. The correlation coefficient between the predicted concentrations by PLS and the prepared concentrations was 0.95 at −4.7 °C, but was 0.07 at 22 °C. Thus, the precision of the determination of creatinine was remarkably improved by using the low-temperature measurement. Index Headings: Biochemical analysis; Low-temperature infrared spectroscopy; Solidification.

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Interstitial Carbon Related Defects in Low-Temperature Irradiated Si: FTIR and DLTS Studies

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.108-109.261 ◽

2005 ◽

Vol 108-109 ◽

pp. 261-266 ◽

Cited By ~ 11

Author(s):

Lyudmila I. Khirunenko ◽

Yu.V. Pomozov ◽

N.A. Tripachko ◽

Mikhail G. Sosnin ◽

A.V. Duvanskii ◽

...

Keyword(s):

Low Temperature ◽

Deep Level Transient Spectroscopy ◽

Deep Level ◽

Absorption Bands ◽

Interstitial Carbon ◽

Intermediate States ◽

Lower Activation ◽

Radiation Induced ◽

Transient Spectroscopy ◽

Interstitial Carbon Atom

The evolution of radiation-induced carbon-related defects in low temperature irradiated oxygen containing silicon has been studied by means of Fourier transform infrared absorption spectroscopy (FTIR) and deep level transient spectroscopy (DLTS). FTIR measurements have shown that annealing of interstitial carbon atom Ci, occurring in the temperature interval 260-300 K, results in a gradual appearance of a number of new absorption bands along with the well known bands related to the CiOi complex. The new bands are positioned at 812, 910.2, 942.6, 967.4 and 1086 cm-1. It has been found that the pair of bands at 910 and 942 cm-1 as well as another set of the bands at 812, 967.4 and 1086 cm-1 display identical behavior upon isochronal annealing, i.e. the bands in both groups appear and disappear simultaneously. The disappearance of the first group occurs at T = 285-300 K while the second group anneals out at T = 310-340 K. These processes are accompanied by an increase in intensity of the bands related to CiOi. It is suggested that intermediate states (precursors) are formed upon the transformation from a single (isolated) Ci atom to a stable CiOi defect. The results obtained in DLTS studies are in agreement with the FTIR data and show unambiguously the formation of CiOi precursors with slightly lower activation energy for the hole emission as compare to that for the main CiOi state.

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Detection by low-temperature magnetic circular-dichroism spectroscopy of optical absorption bands due to molybdenum (V) in the form of xanthine oxidase giving the Desulpho Inhibited e.p.r. signal

Biochemical Journal ◽

10.1042/bj2330107 ◽

1986 ◽

Vol 233 (1) ◽

pp. 107-110 ◽

Cited By ~ 3

Author(s):

J Peterson ◽

C Godfrey ◽

A J Thomson ◽

G N George ◽

R C Bray

Keyword(s):

Circular Dichroism ◽

Low Temperature ◽

Xanthine Oxidase ◽

Absorption Spectra ◽

Magnetic Circular Dichroism ◽

Electronic Absorption Spectra ◽

Visible Region ◽

Absorption Bands ◽

Magnetic Circular Dichroism Spectroscopy ◽

Circular Dichroïsm

The magnetic circular-dichroism (m.c.d.) spectra in the temperature range 1.5-100 K and the electronic absorption spectra at 4.2 and 295 K were measured for a number of desulpho xanthine oxidase derivatives. There were no significant differences between the absorption spectra that could be attributed to molybdenum. However, the visible-region m.c.d. spectrum of the ethanediol-treated metalloprotein (which gives rise to the Desulpho Inhibited e.p.r. signal) contained features assignable to Mo(V) absorption bands. This is the first report of the detection of optical bands of Mo(V) in an enzyme in the presence of other chromophoric centres.

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