Search results for "Absorption"
showing 10 items of 2701 documents
Nonlinear refraction and absorption of spectrally tuneable picosecond pulses in carbon disulfide
2021
Abstract We analyze the spectral dependence of the nonlinear refractive index and nonlinear absorption coefficient of carbon disulfide (CS2) in the spectral range of 400–1100 nm using picosecond laser pulses. An increase of the nonlinear refractive index of CS2 at the shorter wavelength region compared with the near infrared region (9 × 10−14 cm2 W−1 (λ = 700 nm) and 4 × 10−14 cm2 W−1 (λ = 1000 nm), respectively) follows by a decrease of this parameter at the wavelengths below 600 nm. We compare the spectral dependences of the lower- and higher-order nonlinear absorption coefficients in carbon disulfide. The three-photon absorption coefficient was found to be maximal at λ = 1000 nm (β3PA = …
Self-trapped exciton in Li2GeO3
1997
Abstract Self-trapped excitons (STE) are discovered in Li2GeO3 crystal. The PL band at 2.7 eV with a strong Stoke's shift is excited in the intrinsic absorption range of Li2GeO3 crystal, in which the optical gap is situated at 6 eV. The activation energy of the STE luminescence thermal quenching is not monoenergetic and is situated in the range 40–100 meV. The luminescence is strongly polarized. The decay kinetics can be characterized by τ = 0.9 ms at 45 K. At 5 K it can be approximated by fast (0.6 ms) and slow (4–2.5 ms) components. Decay kinetics is determined by triplet state of STE splits in zero magnetic field. Two different excited triplet states (centers) have the average ODMR param…
Anomale röntgenstreuung zur erforschung makromolekularer strukturen
1982
The possibilities of anomalous X-ray scattering for the investigation of semi- or noncrystalline macromolecular structures are discussed on the grounds of the first successful measurements of anomalous scattering of iron in dissolved hemoglobin. As anomalous scattering of this kind of material is limited to the near vicinity of the X-ray absorption edges, the use of synchrotron radiation appears to be obligatory. The anomalous dispersion of the atomic form factors slightly increases with the atomic number. Anomalous dispersion is nearly doubled when going from the K-absorption edge to the LIII-absorption edge and from there to the Mv- absorption edge. Therefore, the use of anomalous dispers…
First-principles simulations of the electronic density of states for superionic Ag2CdI4 crystals
2011
Abstract Energy band dispersion calculations have been performed for Ag 2 CdI 4 superionic within a framework of local density approximation (Perdew–Zunger parameterization) exploiting the first-principles CASTEP computer code. The ab-initio electronic structure simulations were performed for both ( I 4 and I 42 m ) types of e -Ag 2 CdI 4 crystalline structures. Principal optical functions as well as the density of electronic states in the spectral range of inter-band optical transitions (2.5 eV–20 eV) were determined. Theoretically calculated absorption coefficients derived from the obtained band structure are compared with appropriate experimental data.
Transient color centers in complex oxide crystals
2005
The present work is devoted to investigation of induced by a pulsed electron beam (E = 0.25 MeV, τ = 10 ns) transient color centers in pure Gd3Ga5O12, YAlO3 and LiNbO3 single crystals. The relaxation of induced absorption of the crystals was studied within 0-5000 ns range. The origin and nature of transient color centers responsible for induced absorption was discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
The electron beam induced short lived absorption in PLZT optical ceramics
2013
Abstract The short lived absorption induced by a pulsed electron beam in the led–lanthanum–zirconate–titanate (PLZT) optical ceramics was studied. The measured absorption spectrum covers 1.1–2.9 eV energy range and consists of several strongly overlapping peaks. The rise of the absorption is delayed with respect to the excitation pulse, due to charge carrier migration before trapping at centers responsible for the absorption. The formation rate of absorption centers and decay rate of absorption depend on the photon energy. The kinetics of short lived absorption varies over spectrum and can be approximated with a stretched exponent. The stretched exponent parameters indicate that the local d…
The correlation of the 7.6 eV optical absorption band in pure fused silicon dioxide with twofold-coordinated silicon
1992
Abstract The optical absorption band at 7.6 eV, which appears in oxygen deficient pure silica, does not correlate with any ESR signal in non-irradiated samples. Longlasting illumination at 80 K in the range of its absorption leads to an increase of the absorption band at 5 eV. Subsequent heating to 290 K restores the initial absorption. These data can be explained as photodissociation and thermal recreation of a complex defect containing a twofold-coordinated silicon defect. This complex defect is responsible for the 7.6 eV absorption band.
Momentum-resolved photoelectron absorption in surface barrier scattering on Ir(111) and graphene/Ir(111)
2017
Physical review / B 96(15), 155108 (2017). doi:10.1103/PhysRevB.96.155108
Absorption edge in silica glass
2005
Measurements of optical absorption in the v-UV range in a variety of silica glass are used to determine the width of the absorption edge (Urbach energy). Measured values range from 60 meV up to 180 meV. So high a variability over silica types is tentatively ascribed to the different disorder degree, which characterizes different materials.
Nonlinear Optical Characterization of InP@ZnS Core-Shell Colloidal Quantum Dots Using 532 nm, 10 ns Pulses
2021
InP@ZnS core-shell colloidal quantum dots (CQDs) were synthesized and characterized using the z-scan technique. The nonlinear refraction and nonlinear absorption coefficients (γ = −2 × 10−12 cm2 W−1, β = 4 × 10−8 cm W−1) of these CQDs were determined using 10 ns, 532 nm pulses. The saturable absorption (β = −1.4 × 10−9 cm W−1, Isat = 3.7 × 108 W cm−2) in the 3.5 nm CQDs dominated at small intensities of the probe pulses (I ≤ 7 × 107 W cm−2) followed by reverse saturable absorption at higher laser intensities. We report the optical limiting studies using these CQDs showing the suppression of propagated nanosecond radiation in the intensity range of 8 × 107–2 × 109 W cm−2. The role of nonline…