Related Experiment Video
Updated: Aug 9, 2026
07:26
Synthesis and Microdiffraction at Extreme Pressures and Temperatures
Published on: October 7, 2013
Optical versus thermal transitions in solids at high pressure
H G Drickamer1, C W Frank, C P Slichter
1School of Chemical Sciences and Materials Research Laboratory, University of Illinois, Urbana, Ill. 61801.
Summary
High pressure can alter material properties by inducing electronic transitions. This study links optical absorption data to predict pressure-induced electronic state changes in iron compounds, aiding material science research.
Area of Science:
- Solid State Physics
- Materials Science
- Spectroscopy
Background:
- Pressure-induced electronic transitions are common in materials.
- Mössbauer spectroscopy reveals pressure-dependent changes in iron's oxidation and spin states.
- Optical absorption measures energy differences between electronic states.
Purpose of the Study:
- To correlate optical absorption peak energy and width with thermal energy differences under pressure.
- To predict the pressure at which new ground states form using optical data.
- To validate these predictions with experimental iron complexes.
Main Methods:
- Relating optical absorption peak energy and half-width to thermal energy differences.
- Analyzing pressure-dependent optical absorption spectra.
- Comparing predictions with experimental data for ferric hydroxamates and ferrous phenanthroline complexes.
Main Results:
- Optical peak broadening under pressure indicates differing ground and excited state force constants.
- A method is established to predict pressure-induced ground state transitions from optical data.
- Predictions show qualitative agreement with experimental reductions of Fe(III) and spin transitions of Fe(II).
Conclusions:
- Optical absorption spectroscopy provides a predictive tool for pressure-induced electronic transitions.
- Understanding force constant differences is crucial for interpreting pressure-dependent spectral broadening.
- This approach is applicable to iron compounds undergoing oxidation state or spin state changes.
More Related Videos
08:42High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions
Published on: October 10, 2014
07:48An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions
Published on: June 18, 2020
Related Concept Videos
02:31Phase Transitions
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to occupy...
01:21Phase Transitions
A phase transition is the process in which a substance changes from one state of matter to another, like from a solid to a liquid, liquid to gas, or vice versa, at a specific temperature and under given pressure conditions. This change is spontaneous and is affected by alterations in temperature and pressure. These parameters impact the strength of the forces between molecules (intermolecular forces) in the substance.During a phase transition, both the initial and final phases of the substance...
01:19Phase Diagram
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
01:24Phase Diagram
A phase diagram is a graphical representation of the physical states of a substance under different conditions of temperature and pressure. It shows the boundaries between solid, liquid, and gas phases and the conditions at which these phases coexist in equilibrium. An area in a phase diagram represents a single phase, whereas lines or phase boundaries represent the equilibrium between two phases.In the phase diagram of water, the boundary line between the solid and liquid states illustrates...
00:59States of Matter and Phase Changes
The internal energy of a substance—the total kinetic energy of all its molecules and the potential energy of their associated forces—depends on the strength of the intermolecular forces in the condensed phases and the pressure exerted on the substance. The internal energy of a substance is the highest in the gaseous state, the lowest in the solid state, and intermediate in the liquid state. Phase transitions are caused by changes in physical conditions, such as temperature and pressure, that...
02:39Phase Diagrams
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...