Many body interactions in binary ionic solids

The room-temperature Raman spectra of aragonite, magnesite and dolomite have been recorded up to 30 GPa and 25 GPa, respectively and no phase changes were observed during compression, unlike calcite. The effect of temperature on the room-pressure Raman spectra of calcite, aragonite, magnesite and dolomite is reported up to 800–1100 K. The measured relative pressure and temperature-shifts of the Raman lines are greater for the lattice modes than for the internal modes of the CO3 groups. These shifts are used to calculate the mode anharmonic parameters of the observed Raman modes; they are negative and their absolute values are smaller (close to 0) for the internal CO3 modes than for the lattice modes (4–17 10−5 K−1). The temperature shifts of the lattice modes in calcite are considerably larger than those for dolomite and magnesite, and a marked non-linear increase in linewidth is observed above 400° C for calcite. This is consistent with an increasing relaxational component to the libration of the CO3 groups about their threefold axes, premonitory to the rotational order-disorder transition at higher temperature. This behaviour is not observed for the other calcite structured minerals in this study. We examine systematic variations in the lattice mode frequencies and linewidths with composition, to begin to understand these differences in their anharmonic behaviour. Finally, we have used a simple Debye-Waller model to calculate atomic displacements in calcite, magnesite and dolomite with increasing temperature from the vibrational frequency data, to provide a direct comparison with atomic positional data from high-temperature structure refinements.

Raman spectroscopic studies of carbonates part I: High-pressure and high-temperature behaviour of calcite, magnesite, dolomite and aragonite

3D and 4D Lithography of Untethered Microrobots

The phonon dispersion relations for the lowest-ten external branches, and for wave vectors along the optic axis, ahve been measured in calcite, CaC${\mathrm{O}}_{3}$, at room temperature, by means of inelastic-neutron-scattering techniques. The results are shown to be consistent with a simple shell model containing ten adjustable parameters.

Lattice Dynamics of Calcite

A mitochondrial-targeted two-photon fluorescent formaldehyde probe (MT-FA) with a large emission enhancement was developed. MT-FA could image formaldehyde in the mitochondria of living cells for the first time, and also could image formaldehyde in living liver tissue slices.

Development of a mitochondrial-targeted two-photon fluorescence turn-on probe for formaldehyde and its bio-imaging applications in living cells and tissues

The technique of two-photon-absorption spectroscopy with polarized laser-light is applied to localized excitations of 4f-electrons in crystals. The relevant selection rules are discussed. A method is outlined for the unique determination of the relative magnitude of partial transition-probabilities with different types of symmetry using linear and circular polarization of the incident light. The anisotropy of the two-photon absorption has been measured in single crystals of cubic CaF2:Eu2+ at five different wavenumbers. The relative intensities of transitions belonging to the three different types of symmetry active in two-photon absorption are constant in the range of the e-band (26,000 to 29,000 cm−1) but differ from these values at 37,700 cm−1 in the range between the e- and the t-band. This result is discussed in the frame of existing interpretations of the 4f65d-configuration of Eu2+ in CaF2.



In dieser Arbeit werden angeregte Zustande lokalisierter 4f-Elektronen in Kristallen mit den Mitteln der Zwei-Photonen-Spektroskopie mit Lasern untersucht. Dabei werden die einschlagigen Auswahlregeln diskutiert und eine Methode zur eindeutigen Bestimmung der Intensitat von Teilubergangswahrscheinlichkeiten verschiedenen Symmetrietyps angegeben, bei der linear und zirkular polarisiertes Laserlicht benutzt wird. Die Anisotropie der Zwei-Photonen-Absorption in kubischen Kristallen von CaF2:Eu2+ wurde bei funf verschiedenen Frequenzen bestimmt. Dabei ergab sich, das die relative Intensitat von drei in Zwei-Photonen-Absorption aktiven Teilubergangswahrscheinlichkeiten konstant sind im Bereich der e-Bande (26000 bis 29000 cm−1), aber davon verschieden sind zwischen e-und t-Bande bei 37700 cm−1. Dieses Ergebnis wird im Rahmen zweier verschiedener Interpretationen der 4f65d-Konfiguration des Eu2+ in CaF2 diskutiert.

Two-Photon Absorption of CaF2:Eu2+†

Normal frequencies and normal modes of the lattice vibrations for the wave vector |y| = 0 have been calculated for the isomorphic series of NaNO3, CaCO3, and MgCO3. The calculated frequencies of the infrared- and Raman-active modes have been fitted to the experimentally known values for T = 300 °K by variation of the coupling constants. Three different models have been used: a) In model 1 only the short-range interactions by central forces have been taken into account. b) In model 2 the Coulomb-interaction has been included (rigid-ion model). c) In model 3 the anisotropic polarizability of the anion has been considered in addition (shell model). The best fit has been obtained with the shell-model. The calculated frequencies and eigen-vectors are given and discussed in comparison with experimental results.



Fur die isomorphe Reihe der Kristalle NaNO3, CaCO3 und MgCO3 wurden Eigenfrequenzen und Schwingungsformen der auseren Gitterschwingungen fur den Wellenvektor |y| = 0 bestimmt, indem die berechneten Frequenzen der ultrarot- und Raman-aktiven Eigenschwingungen an die bei 300 °K ermittelten experimentellen Werte durch Variation der Kopplungsparameter angepast wurden. Fur die Berechnung wurden drei verschiedene Modelle benutzt: a) Im Modell I wurden nur die kurzreichweitigen Zentralkrafte betrachtet. b) Im Modell 2 wurde daruber hinaus die Coulomb-Wechselwirkung berucksichtigt (Modell des starren Ions). c) Im Modell 3 wurde zusatzlich noch die anisotrope Polarisierbarkeit der Anionenkomplexe beachtet (Schalenmodell). Die beste Anpassung wurde mit dem Schalenmodell erzielt. Eigenfrequenzen und -vektoren werden angegeben und mit experimentellen Ergebnissen verglichen.

Lattice dynamics of crystals of the calcite structure. I. Normal frequencies and normal modes at zero wave vector

Relations for the Raman scattering efficiency of polaritons in uniaxial piezoelectric crystals have been formulated for general directions of the wave vector. These relations are well suited for evaluating experimental data on the various mechanisms of the electron-lattice interaction. For this purpose a phenomenological description of the dispersion of polaritons has also been given, starting from Huang's equations of motion of long wavelength polar lattice vibrations. The case of large wave vectors (k ≫ ωph./c, angular dispersion of phonons) is included in the theory.



Fur Polaritonen in einachsigen piezoelektrischen Kristallen, deren Wellenzahlvektor eine allgemeine Richtung hat, wird der Wirkungsgrad der Ramanstreuung berechnet. Mit dieser Theorie sollen ails dem Experiment insbesondere Daten fur die verschiedenen Mechanismen der Elektron Gitter-Wechselwirkung gewonnen werden. Die Berechnung des Wirknngsgrades erfolgt uber eine phanomenologische Beschreibung der Dispersion der Polaritonen, ausgehend von den Huangschen Gleichulgen fur polare Phononen groser Wallenlange. Der Fall groser Wellenzahlvektoren (k ≫ ω/c, Richtungsdispersion der Phononen) ist in der Theorie enthalten.

Raman scattering intensity of polaritons for general wave vectors I. Theory

Anisotropy of the Two‐Photon Absorption of Cubic CaF2:Eu2+

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

G. Schaack

Author Tools

Chat about Author

Papers

Two-Photon Absorption of CaF2:Eu2+†

Lattice dynamics of crystals of the calcite structure. I. Normal frequencies and normal modes at zero wave vector

Raman scattering intensity of polaritons for general wave vectors I. Theory

Anisotropy of the Two‐Photon Absorption of Cubic CaF2:Eu2+