Absorption (logic)

About: Absorption (logic) is a research topic. Over the lifetime, 5733 publications have been published within this topic receiving 236302 citations.

Spectroscopy of Cr 3 + and Cr 4 + ions in forsterite

Abstract: Fluorescence and site-selective excitation spectra of chromium-activated forsterite at 10 K are reported. It is found that a high-field ${\mathrm{Cr}}^{3+}$ site in inversion symmetry emits sharp ${\mathit{R}}_{1}$ line fluorescence, while a low field ${\mathrm{Cr}}^{3+}$ site in mirror symmetry produces $^{4}$${\mathit{T}}_{2}$ broadband emission. The dominant absorption in the visible is shown to be the $^{3}$${\mathit{A}}_{2}$${\ensuremath{\rightarrow}}^{3}$${\mathit{T}}_{1}$${(}^{3}$F) transitions of ${\mathrm{Cr}}^{4+}$ in tetrahedral sites. In the near-infrared region, three sharp lines from ${\mathrm{Cr}}^{4+}$ were observed and are assigned to the transition from the $^{3}$${\mathit{A}}_{1}$${(}^{3}$${\mathit{T}}_{2}$) spin triplet to the $^{3}$${\mathit{A}}_{2}$ ground state. The energy-level splittings of ${\mathrm{Cr}}^{4+}$ due to an orthorhombic-distorted field with spin-orbit coupling are discussed.

Surface and bulk electronic structure of ScN ( 001 ) investigated by scanning tunneling microscopy/spectroscopy and optical absorption spectroscopy

Abstract: $\mathrm{ScN}(001)$ $1\ifmmode\times\else\texttimes\fi{}1$ surfaces have been prepared by growing $\mathrm{ScN}$ on $\mathrm{MgO}(001)$ using radio frequency molecular beam epitaxy. In situ ultrahigh vacuum scanning tunneling spectroscopy indicates that the Fermi level at the surface lies slightly above the $\mathrm{Sc}\phantom{\rule{0.3em}{0ex}}3d$ conduction band edge, which is attributed to a downward band bending at the surface. In situ scanning tunneling microscopy is used to image the $\mathrm{Sc}$ and $\mathrm{N}$ atom sublattices. While only one atom $(\mathrm{Sc})$ appears at small negative bias, both atoms ($\mathrm{Sc}$ and $\mathrm{N}$) appear at certain positive sample biases due to the partially ionic nature of the bonding. Charge accumulation near ionized subsurface donors is evident from the long-range topographic distortions at the surface. The combination of tunneling spectroscopy and optical absorption results show that $\mathrm{ScN}$ has an indirect bandgap of $0.9\ifmmode\pm\else\textpm\fi{}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and a direct transition at $2.15\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$.

Quantum state-resolved probing of strong-field-ionized xenon atoms using femtosecond high-order harmonic transient absorption spectroscopy.

Abstract: Femtosecond high-order harmonic transient absorption spectroscopy is used to resolve the complete $|j,m⟩$ quantum state distribution of ${\mathrm{Xe}}^{+}$ produced by optical strong-field ionization of Xe atoms at 800 nm. Probing at the Xe ${N}_{4/5}$ edge yields a population distribution ${\ensuremath{\rho}}_{j,|m|}$ of ${\ensuremath{\rho}}_{3/2,1/2}\ensuremath{\mathbin:}{\ensuremath{\rho}}_{1/2,1/2}\ensuremath{\mathbin:}{\ensuremath{\rho}}_{3/2,3/2}=75\ifmmode\pm\else\textpm\fi{}6\text{ }\mathrm{\text{:}}12\ifmmode\pm\else\textpm\fi{}3\text{ }\mathrm{\text{:}}13\ifmmode\pm\else\textpm\fi{}6%$. The result is compared to a tunnel ionization calculation with the inclusion of spin-orbit coupling, revealing nonadiabatic ionization behavior. The sub-50-fs time resolution paves the way for tabletop extreme ultraviolet absorption probing of ultrafast dynamics.

Laser cooling in the condensed phase by frequency up-conversion.

Abstract: Frequency up-conversion has been observed in fluid solutions of the laser dye, rhodamine 101, when excited at 1.96 eV into the low energy absorption tail 0.15 eV from the 0-0 band origin. The emission intensity is temperature dependent and is demonstrated to be an excellent measurement of the temperature of the sample. We show for the first time how intense laser irradiation in this spectral region leads to the removal of thermal energy by the frequency up-conversion process, and thus lowers the temperature of the sample. A decrease in temperature at a rate of $0.7\mathrm{K}{\mathrm{h}}^{\ensuremath{-}1}$ is demonstrated for a sample with a $3\mathrm{J}{\mathrm{K}}^{\ensuremath{-}1}$ heat capacity, when irradiated with 350 mW of laser light at 1.96 eV.

High-pressure structural transformation of SiO 2 glass up to 100 GPa

Abstract: We have conducted structure measurements of ${\text{SiO}}_{2}$ glass under high pressure up to 100 GPa by an energy-dispersive x-ray diffraction method with synchrotron white x rays. X-ray diffraction data indicate that ${\text{SiO}}_{2}$ glass transforms from a fourfold- to a sixfold-coordinated structure at pressures between 20 and 35 GPa, and then behaves as an amorphous polymorph having a sixfold-coordinated structure at least up to 100 GPa. These results are consistent with those of density measurements by an x-ray absorption method with monochromatic x rays, except for the slight difference in the pressure range where the transformation from a fourfold- to a sixfold-coordinated structure is completed. They are also mostly consistent with those of structure measurements by an x-ray diffraction method with monochromatic x rays but some aspects are quantitatively different. It is presumed that the irradiation of white x rays may have relaxed the structure and deviatoric stresses of ${\text{SiO}}_{2}$ glass in this study.