Infrared electronic absorption in a single-component molecular metal
Akiko Kobayashi1, Masaaki Sasa, Wakako Suzuki
1Research Centre for Spectrochemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|January 15, 2004
Summary
Single-component molecular metals like Ni(tmdt)2 exhibit unique low-energy electronic absorption. This suggests molecular conductors possess exceptionally small highest occupied molecular orbital-lowest unoccupied molecular orbital gaps.
Area of Science:
- Materials Science
- Solid-State Physics
- Molecular Chemistry
Background:
- The study focuses on Ni(tmdt)2, a novel single-component molecular metal exhibiting a stable metallic state at low temperatures.
- Extended-TTF ligands are crucial in designing molecular materials with unique electronic properties.
Purpose of the Study:
- To investigate the electronic properties of Ni(tmdt)2 using infrared spectroscopy.
- To understand the relationship between molecular structure and conductivity in single-component molecular conductors.
Main Methods:
- Infrared (IR) spectroscopy was employed to analyze the crystal of Ni(tmdt)2.
- Comparative analysis of IR spectra for similar molecules, ranging from metallic to semiconducting, was performed.
Main Results:
- An extremely low-energy electronic absorption was observed around 2200 cm-1 in Ni(tmdt)2.
- Systematic shifts in absorption peaks correlated with the transition from metallic to semiconducting behavior in related compounds.
Conclusions:
- Single-component molecular conductors, exemplified by Ni(tmdt)2, are characterized by unusually small HOMO-LUMO gaps.
- The observed electronic absorption provides insights into the fundamental electronic structure of these advanced molecular materials.
More Related Videos
07:55Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering
Published on: April 17, 2018
06:53Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Related Concept Videos
02:26Photoelectric Effect
When light of a particular wavelength strikes a metal surface, electrons are emitted. This is called the photoelectric effect. The minimum frequency of light that can cause such emission of electrons is called the threshold frequency, which is specific to the metal. Light with a frequency lower than the threshold frequency, even if it is of high intensity, cannot initiate the emission of electrons. However, when the frequency is higher than the threshold value, the number of electrons ejected...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:32UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...
01:14Molecular Spectroscopy: Absorption and Emission
Molecules possess discrete energy levels called quantum states. Unlike atoms, which have simpler energy levels, molecules possess additional rotational and vibrational energy levels. Each energy level is separated by an energy gap, with the gaps between adjacent electronic, vibrational, and rotational levels varying significantly. The three types of energy levels in a diatomic molecule are shown in Figure 1.
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this process,...
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...