Showing papers on "Absorption band published in 1988"
TL;DR: In this article, in-situ IR spectroscopy of adsorbed hydrogen on polycrystalline Pt, Rh, Ir and single crystal Pt(111) electrodes in acid solution allowed the identification of a new type of this adsorbate.
161 citations
TL;DR: In this article, the authors investigated the initial step of charge separation at 10 K with 100-fs time resolution in reaction centers from Rhodopseudomonas viridis and Rhodobacter sphaeroides as well as in reaction centres from the latter species in which one of the two monomeric bacteriochlorophyll (B) molecules has been removed by treatment with borohydride.
Abstract: The initial step of charge separation at 10 K has been monitored with 100-fs time resolution in reaction centers from Rhodopseudomonas viridis and Rhodobacter sphaeroides as well as in reaction centers from the latter species in which one of the two monomeric bacteriochlorophyll (B) molecules has been removed by treatment with borohydride. Upon excitation at 870 nm, the absorbance changes measured at several wavelengths in the near-infrared absorption bands of the pigments, and notably at the absorption maximum of the B molecule(s), give no indication of a detectable concentration of B-. Instead, the appearance of the cation radical of the dimeric primary electron donor (P) and of the bacteriopheophytin anion develops in concert with the decay of P*. An initial bleaching of the 850-nm band in reaction centers from Rho- dopseudomonas uiridis is consistent with an assignment of at least a large fraction of this band to the high-energy exciton component of P. Upon excitation of the B molecule(s) around 600 nm in the three types of reaction centers investigated, ultrafast energy transfer leads to the formation of P* in less than 100 fs. Under these conditions, a fast transient bleaching decaying with a 400-fs time constant is observed within the absorption band of B. This transient is also present upon preferential excitation of the bac- teriopheophytins in the reaction center of Rhodopseudomonas uiridis.
159 citations
TL;DR: In this paper, a detailed theortical study of the photodissociation of H2O and D2O in the first absorption band (λ∼165 nm) is presented.
Abstract: We report a detailed theortical study of the photodissociation of H2O and D2O in the first absorption band (λ∼165 nm). The calculations are three dimensional and purely quantum mechanical. They include an ab initio potential energy surface for the A state and a calculated SCF dipole moment function for the X→A transition. The dynamical calculations are performed within the infinite‐order‐sudden approximation for the rotational degree of freedom of OH and the LHL approximation for the masses. The resulting vibrational–translational motion is then treated exactly in two dimensions using hyperspherical coordinates. This study does not include any adjustable parameters. The thermally averaged total absorption spectra for H2O and D2O agree perfectly with the experimental spectra. Even finer details such as the progression of ‘‘vibrational’’ structures are well reproduced. They are not induced by any selective absorption but can be explained on the basis of the A state potential energy surface and details o...
150 citations
TL;DR: In this article, the effect of laser-induced excitation on the luminescence and transient optical absorption induced by irradiation of crystalline SiO2 with an electron pulse have been studied.
Abstract: Linear polarisation, with respect to the z axis, and the effect of the subsequent laser-induced excitation on the luminescence and transient optical absorption induced by irradiation of crystalline SiO2 with an electron pulse have been studied. It is found that the luminescence spectrum consists of two bands peaked at 2.8 eV and at 2.5 eV and that the transition dipole moment of the former, which has been shown to be intrinsic, is nearly parallel to the z axis, while that of the latter is parallel to the x axis. In addition to the 5.2 eV transient optical absorption band, a satellite band at 4.2 eV is found to be induced by irradiation with an electron pulse. For both of these bands, the transition dipoles are found not to be parallel to any of the crystalline axes. Subsequent irradiation with a 4.0 or 5.6 eV laser pulse of a specimen irradiated with an electron pulse is found to eliminate both of these transient optical absorption bands and the 2.8 eV luminescence band. In view of previous work on optically detected magnetic resonance and volume changes induced by electron pulse irradiation, it is concluded that the 5.2 and 4.2 eV transient optical absorption bands and the 2.8 eV luminescence band are associated with self-trapped excitons. The existing models of self-trapped excitons are discussed on the basis of the present experimental results.
147 citations
TL;DR: In both structures, the negative sign of the CD at 265 nm indicates that the twist occurring between DNA molecules is left-handed, and it is shown that this situation is the most frequently encountered in vivo and vitro.
Abstract: Two highly condensed structures of DNA have been analyzed in the circular dichroism (CD) microscope: the cholesteric liquid-crystalline phase of DNA and the nucleus of a dinoflagellate (Prorocentrum micans). In both cases, the DNA shows a helical cholesteric organization, but the helical pitch equals about 2500 nm in the first case and 250 nm in the second one. Since the absorption band of DNA is located at 260 nm, the reflection and absorption bands are well separated in the cholesteric phase of DNA and are overlapping in the dinoflagellate nucleus. However, both structures give a very strong negative CD signal at 265 nm. We show that this very strong signal cannot correspond to a Borrmann effect, i.e., to a superposition of the absorption and reflection bands, but is a differential absorption of left versus right circularly polarized light. This anomalous differential absorption is probably due to a significant scattering of light, inside of the structure, which produces a resonance phenomenon in the absorption band of the chromophore. Therefore, for any helical structure containing a chromophore, the apparent CD can be expressed as CD = [(epsilon L - epsilon R)cl] + (psi L - psi R) + (SL - SR) The first term is true absorption and is located in the absorption band of the chromophore, and the last term is true scattering and is observed at the wavelength corresponding to the helical pitch of the structure. The second term (psi L - psi R) corresponds to the anomalous differential absorption observed in dense superhelical structures of DNA. It superimposes to the first term in the absorption band of the chromophore. psi L - psi R is a measure of the perfection of the helical structure and of the density of chromophores in the material. Intercalative dyes [ethidium bromide and meso-tetrakis(4-N-methylpyridyl)porphine (H2TMpyP-4) and its nickel(II) derivative (NiIITMpyP-4)] were inserted in the dinoflagellate chromatin. The CD signal recorded in their absorption band mimics the signal observed in the absorption band of DNA. In both structures, the negative sign of the CD at 265 nm indicates that the twist occurring between DNA. In both structures, the negative sign of the CD at 265 nm indicates that the twist occurring between DNA molecules is left-handed, and we show that this situation is the most frequently encountered in vivo and vitro.
116 citations
TL;DR: In this paper, a thermochromic derivative of salicylideneaniline, N,N′-bis(salicylide)-p-phenylenediamine (BSP), has been prepared and subjected to structural and optical studies in the crystalline state.
Abstract: A thermochromic derivative of salicylideneaniline, N,N′-bis(salicylidene)-p-phenylenediamine (BSP), has been prepared and subjected to structural and optical studies in the crystalline state. An X-ray crystallographic analysis has shown that the molecules are planar and are stacked in a parallel fashion to form one-dimensional columns. The interplanar spacing has been found to be quite short, suggesting the existence of an intermolecular charge-transfer interaction. The molecule contains fairly short O–H··· N hydrogen bonds, the strength of which is manifested in an OH stretching absorption band in the infrared region, showing considerable broadening and a low-frequency shift. The BSP crystals are remarkably thermochromic, and visible absorption and emission spectral changes with temperature have been interpreted in terms of an intramolecular proton transfer from the hydroxyl oxygen to imine nitrogen through the O–H··· N hydrogen bond. The emission spectra have also been examined under high pressures.
104 citations
TL;DR: In this article, the photofragmentation of HOD in the first absorption band was investigated and the final vibrational distributions for OD and OD are relatively broad indicating strong final state interaction.
Abstract: We investigate the photofragmentation of HOD in the first absorption band. Full three‐dimensional quantum mechanical calculations on an ab initio excited state potential are presented. They are based on the IOS approximation for the rotational (bending) degree of freedom. The remaining two‐dimensional problem is treated exactly using hyperspherical (polar) coordinates. HOD absorption spectra are compared with recently published results for H2O and D2O. Dissociation of the vibrational ground state favors the production of OD fragments, in agreement with physical intuition. The final vibrational distributions for OH and OD are relatively broad indicating strong final state interaction. They are broader for OD but inverted for OH products. Cross sections for the dissociation of vibrationally excited stretching states are also compared with those for H2O and a strong isotope effect is found. The branching ratio depends significantly on the initial vibrational state of the parent molecule. The quantum mechanic...
102 citations
TL;DR: In this paper, photo-induced defect states are located on individual chains, and not associated with interchain defects, and the results are discussed in terms of the photoinduced polaron and kink-soliton models.
Abstract: Photo-induced absorption effects have been investigated in [Pt(en) 2 ][Pt(en) 2 Cl 2 ] (ClO 4 ) 4 single crystals. When the crystals are irradiated at 77 K by the light within the charge-transfer absorption band (CT band) or higher, two absorption bands (A and B) are observed below the CT band. Their intensities increase linearly with the total excitation light flux at low excitation level. The photo-induced absorption bands are stable at 77 K, but are not observed at room temperature. The A and B bands are induced only by the light with E // chain and preferencially polarized for E // chain, suggesting that the photo-induced defect states are located on individual chains, and not associated with interchain defects. The results are discussed in terms of the photo-induced polaron and kink-soliton models.
86 citations
TL;DR: Since it is not necessary to obtain information on the fluorescence spectra of completely relaxed states, this method for the estimation of relaxation times may have advantages in studies of proteins compared with the conventional relaxation shift method, and may produce complementary information to that obtained by nanosecond time-resolved spectroscopy.
Abstract: Studies on the dependence of indole and tryptophan fluorescence emission spectra on excitation wavelength, lambda ex, show that the emission shifts to longer wavelengths for red-edge excitation in different solid and viscous solvents. In solid systems the spectral shifts for excitation in the range from 290 to 310 nm can reach tens of nm, and they are more significant than changes of lambda ex. In a viscous medium the magnitude of this effect is shown to be directly related to the dipole-reorientational relaxation of solvent molecules in the environment of the chromophore, which allows the relaxation times to be estimated. The method involves simple steady-state measurements of fluorescence spectra at the maximum and at the red edge of the absorption band. Since it is not necessary to obtain information on the fluorescence spectra of completely relaxed states, this method for the estimation of relaxation times may have advantages in studies of proteins compared with the conventional relaxation shift method, and may produce complementary information to that obtained by nanosecond time-resolved spectroscopy.
77 citations
TL;DR: In this paper, the authors examined the relation between photodissociation dynamics and the form of the total absorption spectrum for H2O in the first absorption band and showed that the series of weak structures on top of the broad continuum is due to symmetric stretch motion in the excited state.
Abstract: We examine the relation between photodissociation dynamics and the form of the total absorption spectrum for H2O in the first absorption band. Application of an exact time dependent formalism gives a direct and intuitive relation between molecular motion and spectral features. We show that the series of weak structures on top of the broad continuum is due to symmetric stretch motion in the excited state. The spacing between the structures is, essentially, given by the frequency associated with this motion. In addition, we present some excited state eigenfunctions, which provide a direct connection between the structured spectrum, the final product distributions, and the dynamics.
74 citations
TL;DR: In this paper, the ν2 bands for dilute solutions of CH3CN and (CH3)3CCN in a range of aprotic and protic solvents were studied.
Abstract: The CN stretching band (ν2) has been studied for dilute solutions of CH3CN and (CH3)3CCN in a range of aprotic and protic solvents. The former induce a low-frequency shift, whereas the latter induce a high-frequency shift relative to dilute solutions in hexane. In both cases there is a large increase in oscillator strength with increasing shift. This is the first example of a solvent that has an absorption band displaying such a dichotomy, the normal behaviour being a progressive low-frequency shift on going via aprotic to protic media. In contrast such ‘normal’ behaviour is observed in the n.m.r. spectra for 14N shifts, but the 13C (CN) shifts are small and seem to be random. In contrast to our previous studies of ‘probe’ molecules the ν2 bands for solutions in water are almost identical to one of the bands in methanol; however, the band in water is a single feature, whilst that in methanol is a doublet, the low-frequency feature being close to the unsolvated region. The interpretation is that MeCN in water is fully monosolvated (hydrogen-bonded), whilst in MeOH it is only ca. 50% monosolvated. However, the effects of temperature changes and studies of mixed water–aprotic solvent systems suggest that this may not be correct, and the possibility that MeCN forms two very weak hydrogen bonds in water is also considered.The methanol doublets are well defined at low temperatures (–50 °C) but resolution is lost on warming. At ca. 50 °C there is only one symmetrical band. For mixed water–aprotic solvent systems, the band remains a narrow singlet throughout the whole mole fraction range, there being no indication of twin bands for hydrogen-bonded and non-hydrogen-bonded units, in contrast with the results for methanol at low temperatures, and our normal experience with other probe molecules. One explanation is that there is rapid equilibrium between hydrogen-bonded and non-hydrogen-bonded units which is fast on the i.r. timescale. Results for other mixed-solvent systems are also reported.We have attempted to use changes in the first and second overtone O—H stretch bands for HOD in D2O on adding MeCN to obtain a measure of the number of hydrogen bonds. This is at best only qualitative because of the proximity of the O—H band for solvated MeCN and the ‘(OH)free’ band for water. However, for MeCN in Me3COH the (OH)free and OH---(NCMe) bands are clearly resolved. The results support the concept that MeCN is dihydrated in water. A less extensive study has been made for 2-cyano-2-methylpropane (Me3CCN) for comparative purposes. The results are broadly similar, the major difference being a reduction in the extent of hydrogen bonding in methanolic solutions.
TL;DR: In this article, the transient optical absorption and luminescence induced by irradiation of amorphous SiO2 with an electron pulse have been measured and it is found that the transient absorption spectra do not depend on impurities and have a strong peak at 5.3 eV and a satellite peak at 4.2 eV.
Abstract: The transient optical absorption and luminescence induced by irradiation of amorphous SiO2 with an electron pulse have been measured. It is found that the transient optical absorption spectra do not depend on impurities and have a strong peak at 5.3 eV and a satellite peak at 4.2 eV. The peak energy of the luminescence band is found to show a blue shift as the time after the pulse increases. By means of a cascade excitation experiment, the absorption band at 5.3 eV, the satellite band at 4.2 eV and the luminescence have been shown to arise from the same centre, which is ascribed to a self-trapped exciton or a metastable excited state accompanied by a large lattice distortion.
TL;DR: The growth of polythiophene has been studied by in situ FT-IR spectroscopy in order to understand in more detail the molecular processes that occur during film formation and cycling.
TL;DR: In this article, it was shown that perturbation of the F center increases the oscillator strengths for these transitions by more than 3 orders of magnitude, and the results of these experiments suggest that the 480nm emission band, previously attributed to the F centre, is also due to a transition-metal impurity.
Abstract: Neutron irradiation of MgAl/sub 2/O/sub 4/ spinel crystals produces an F-center absorption band in the uv accompanied by a broad absorption band in the visible region. Excitation and emission experiments identify the observed structure in the visible absorption band as optical transitions of transition-metal impurity ions perturbed by neighboring F centers. The perturbation of the F center increases the oscillator strengths for these transitions by more than 3 orders of magnitude. The results of these experiments suggest that the 480-nm emission band, previously attributed to the F center, is also due to a transition-metal impurity.
TL;DR: In this article, double modulation Fourier transform infrared reflection absorption spectroscopy was employed for the in situ analysis of low-temperature plasma enhanced chemical vapor deposition formed SiO2 films deposited on HgCdTe, silicon, and aluminum substrates.
Abstract: The sensitivity and selectivity of double modulation Fourier transform infrared reflection absorption spectroscopy for absorbing species on a reflecting surface has been employed for the in situ analysis of low‐temperature plasma enhanced chemical vapor deposition formed SiO2 films deposited on HgCdTe, silicon, and aluminum substrates. An oblique angle of incidence of ∼55° was chosen to yield maximum sensitivity for the longitudinal optical (LO) phonon mode of SiO2 on Si. The peak frequency and shape of the LO mode absorption band varied with the quality of the SiO2 films thus providing a means of in situ assessment of reaction conditions at any stage of film growth. This diagnostic technique can be readily applied to the in situ analysis of dielectric thin films formed under a variety of reaction conditions.
TL;DR: In this article, the synthesis and properties of a fixed-distance symmetric bis-pyrochlorophyllide-a molecule are described, which consists of two MePChlidea moieties sharing a common vinyl group at the 2-position of each macrocycle.
Abstract: The synthesis and properties of a fixed-distance symmetric bis-pyrochlorophyllide-a molecule are described. The molecule, 1, consists of two methyl pyrochlorophyllide-a (MePChlide-a) moieties which share a common vinyl group at the 2-position of each macrocycle. The two chlorophylls are trans to one another across the vinyl linkage. The dihedral angle between the plane of each macrocycle and the vinyl linkage is about 50°. The Qy absorption band of this dimer occurs at 689 nm and is essentially independent of solvent. The band is red-shifted by about 27 run relative to that of MePChlide-a. The fluorescence maximum of 1 occurs at 722 nm. This is a red-shift of 49 nm relative to methyl MePChlide-a. The circular dichroism spectrum of 1 shows strong, nonconservative bands in the red region. The fluorescence quantum yield, fluorescence lifetimes, and picosecond transient absorbance kinetics all exhibit a very strong dependence on solvent polarity. The fluorescence quantum yields of 1 in toluene, butyronitrile, and N, N-dimethyl formamide (DMF) are 0.18, 0.008, and 0.002, respectively. The bleach of the 689 nm band (following excitation with a 1.5-ps, 610-nm laser pulse) recovers with single exponential time constants of 2.51 ns, 100 ps, and 64 ps in toluene, butyronitrile, and DMF, respectively. Possible mechanisms for the polarity-dependent increase of the nonradiative decay rate of 1 are considered.
IBM1
TL;DR: In this article, the infrared reflectance spectra of a thermally grown 30nm SiO2 film on a Si wafer was measured as a function of incident angle and polarization.
Abstract: Infrared reflectance spectra of a thermally grown 30-nm SiO2 film on a Si wafer were measured as a function of incident angle and polarization Spectra measured with s-polarized light resemble the published extinction coefficient for SiO2 The p-polarized spectra show significant distortions at all incident angles Bands change in frequency and intensity and can even invert as the incident angle increases beyond the Brewster angle of the Si substrate Spectral simulations using the classical electromagnetic equations reproduce these distortions
TL;DR: The reversible formation of pure CO islands during the coadsorption of CO and H on Pt{111} has been followed by monitoring the internal stretching vibration as well as the metal-carbon stretch of the CO molecule using infrared reflection-absorption spectroscopy as discussed by the authors.
TL;DR: In this paper, a vibronic coupling model is used for the quantitative interpretation of both the 1 1 B u ← 1 1 A g absorption and the 2 1 A u → 1 1 G fluorescence spectra of 1,8-diphenyl-1,3,5,7-octatetraene (DPO) in cyclohexane solution at 298 K in the absence and in the presence of external electric field (electro-optical spectra).
TL;DR: In this paper, the optical difference spectrum of the excited primary electron donor, P*, in Rb. capsulatus reaction centers has been measured 600 fs after a 350-fs flash at 870 nm.
TL;DR: The major result of this work is that the weak 850-nm absorption band is due, primarily, to the higher energy exciton state of the bacteriochlorophyll special pair, which requires either that a large spectroscopic effect of the protein be introduced, or possibly, that charge transfer states play a majorSpectroscopic role.
TL;DR: In this paper, the fine structure of the absorption band of P in reaction centers of various phototrophic bacteria has been studied at 1.7-70 K. The vibronic structure with a characteristic frequency of ∼ 140 cm−1, zero-phonon line and phonon wing for the 0-0 transition with relatively weak coupling parameters have been resolved.
TL;DR: In this article, the optical band gap and refractive index of tellurium dioxide (TeO 2 ) thin films prepared by vacuum evaporation were evaluated and the defect density was found to be of the order of 6 × 10 20 cm -3.
TL;DR: In this paper, analytical expressions for the total band absorptance and absorption-coefficient distribution function for radiatively important, atmospheric gases are derived from the Malkmus narrowband model and the wide-band approximation of Edwards and Menard.
Abstract: Analytical expressions for the total band absorptance and absorption-coefficient distribution function for radiatively-important, atmospheric gases are derived from the Malkmus narrow-band model and the wide-band approximation of Edwards and Menard. For individual absorption bands, the expressions are functions of the band width, the mean line-half-width to spacing ratio and two parameters describing the spectral variation of the mean line intensity. Procedures to calculate these absorption band parameters directly from the AFGL absorption line data are presented. The accuracy of the formulation is demonstrated by good agreement in the 15-μm CO 2 band, the H 2 O rotational band and the 9.6-μm O 3 band for the absorptances calculated from analytical expressions, line-by-line calculations and available measurements. This formulation thus provides a useful approach to calculate the coupled radiative processes of absorption and multiple scattering due to atmospheric gases and particles.
02 May 1988-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: The 6.3 eV band is enhanced in parallel with the 4.8, 5.4, 6.4 and 6.1 eV bands as mentioned in this paper, which are resolvable at various stages of the growth curves.
Abstract: Optical absorption bands in the ultraviolet region develop during ion implantation. These include the 4.8, 5.4 and 6.1 eV features noted previously in earlier damage studies. In the case of the ion implants additional bands are formed. The region contains features at 5.9, 6.3, 6.4, 6.8 and 6.97 eV which are resolvable at various stages of the growth curves. The 6.3 eV band is enhanced in parallel with the 4.8 and 5.4 eV transitions. All three bands are ascribed to the F+ centre. Models for the higher energy bands are proposed based on complex defects of the oxygen sublattice formed in the high damage density cascade caused by heavy ion implants. In particular, the 6.8 eV band dominates the spectrum after A+ implants. Differences in absorption band strengths are noted for implantation in crystals of different orientation.
TL;DR: In this article, a pump and probe technique for measuring intensity-dependent refractive indices (n2) of waveguide quality thin films was presented, and applied to films of polydiacetylene (CH2)4OCONHOCOC4H9 (PDA•4BCMU).
Abstract: We present a new pump and probe technique for measuring intensity‐dependent refractive indices (n2) of waveguide quality thin films, and we apply it to films of polydiacetylene‐(CH2)4OCONHOCOC4H9 (PDA‐4BCMU). Just below the exciton absorption band, the real part of n2 is negative with magnitude ≊10−7(MW/cm2)−1. The initial fast response of n2 is followed by a slower (∼2.5 ps) decay, in close agreement with the decay of the bleaching of the exciton absorption following resonant excitation. These results are consistent with phase space filling by excitons as the mechanism for the nonlinear index.
TL;DR: In a series of spectra spanning the time interval from about 600 fs to 15 ps, two isosbestic points occurring at 765 run and 798 nm are maintained throughout.
Abstract: The time-evolution of the near-infrared absorption changes accompanying the conversion of the excited primary electron donor, P*, to the radical pair state, P+BPhL−, has been examined in detail in Rhodobacter capsulatus reaction centers. In a series of spectra spanning the time interval from about 600 fs to 15 ps, two isosbestic points occurring at 765 run and 798 nm are maintained throughout. The finding of an isosbestic point at 798 nm in this series of spectra, which encompass the time during which P* decays and BPhL− forms, places severe constraints on the possible reduction of the 800-nm-absorbing monomeric BChlL in the initial stage of the charge-separation process. The near-infrared P* spectrum, which is revealed clearly only when P is excited directly in its long-wavelength absorption band, contains bleaching only of the 855-nm band and a broad featureless transient absorption below 810 nm. This spectrum shows that P does not contribute any significant oscillator strength to the 800-nm ground state absorption band.
TL;DR: In this paper, the authors measured the near ultraviolet absorption spectrum of 2,3-dideuterobutadiene to provide a complete set of experimental Bu←X vibrational intervals and bandwidths for all symmetrically deuterated butadienes.
Abstract: We have measured the near ultraviolet absorption spectrum of 2,3‐dideuterobutadiene to provide a complete set of experimental Bu←X vibrational intervals and bandwidths for all symmetrically deuterated butadienes. These vibrational intervals and bandwidth ratios are compared with the ground state vibrational frequencies and frequency ratios of the molecules. The prominent vibrational frequency interval observed in transitions to the Bu state of butadiene is demonstrated to arise predominantly from a kinetic coupling of the C=C stretching and CH wagging vibrations. The experimental bandwidth ratios are shown to correlate with single quanta of the ground state au CH2 twist frequency interval ratios. From the latter, a plausable decay path for the Bu excited state of butadiene is deduced. The implications of these conclusions on prior and present attempts to determine the butadiene Bu equilibrium geometry and to understand polyene spectroscopy, photochemistry, and photophysics are discussed.
TL;DR: In this article, a very broad infrared emission band at 860 nm was observed for the first time in an inorganic glass, when excitation is performed in the Ti3+ absorption band (T2g → Eg transition in cubic field approximation).
Abstract: The optical properties (absorption and luminescence) of Ti3+ in a P2O5 Na2O-Al2O3 glass have been studied in the temperature range 12 to 300 K. A very broad infrared emission band at 860 nm, has been observed for the first time in an inorganic glass, when excitation is performed in the Ti3+ absorption band (T2g → Eg transition in cubic field approximation). The spectroscopic characteristics of this system are compared with those of the Ti3+ as a dopant in AL2O3 single crystals.
TL;DR: In this article, a new absorption band at 3506 cm −1 was observed in LiNbO 3 doped simultaneously with Mg and Cr. The band is distinctly separated from the well known band at 3485 cm − 1 in undoped crystals and from that near 3540cm − 1 due to MgOH complexes.