This book consists of a collection of review chapters that summarize the
recent progress in the areas of metal and semiconductor nanosized crystals
(nanocrystals). The interest in the optical properties of nanoparticles dates
back to Faraday’s experiments on nanoscale gold. In these experiments,
Faraday noticed the remarkable dependence of the color of gold particles on
their size. The size dependence of the optical spectra of semiconductor nanocrystals
was first discovered much later (in the 1980s) by Ekimov and coworkers
in experiments on semiconductor-doped glasses.
Deviations from Beer’s law (i.e. deviations from the
linearity of absorbance vs. concentration):
– Intermolecular interactions at higher concentrations
– Chemical reactions (species having different spectra)
– Peak width/polychromatic radiation
Beer’s law is only strictly valid with single-frequency radiation
Not significant if the bandwidth of the monochromator is less
than 1/10 of the half-width of the absorption peak at halfheight.
UV-Visible spectra can be
interpreted to help determine
molecular structure, but this
is presently confined to the
analysis of electron behavior
in known compounds.
Information from other
techniques (NMR, MS, IR) is
usually far more useful for
However, UV-Vis evidence
should not be ignored!
The Series ‘Topics in Molecular Organization and Engineering’ was initiated by
the Symposium ‘Molecules in Physics, Chemistry, and Biology’, which was held
in Paris in 1986. Appropriately dedicated to Professor Raymond Daudel, the
symposium was both broad in its scope and penetrating in its detail. The sections
of the symposium were: 1. The Concept of a Molecule; 2. Statics and Dynamics
of Isolated Molecules; 3. Molecular Interactions, Aggregates and Materials; 4.
Molecules in the Biological Sciences, and 5. Molecules in Neurobiology and So-
To examine the role of the distal His42 residue in the catalytic mechanism of pea cytosolic ascorbate peroxidase, two site-directed variants were prepared in which His42 was replaced with alanine (H42A) or glutamic acid (H42E). Electronic spectra of the ferric derivatives of H42A and H42E (pH 7.0, l ¼ 0.10 M, 25.0 °C) revealed wavelength maxima [kmax (nm): 397, 509, % 540sh, 644 (H42A); 404, 516, % 538sh, 639 (H42E)] consistent with a predominantly ﬁveco-ordinate high-spin iron. The speciﬁc activity of H42E for oxidation of L-ascorbate (8.2 ± 0.
Chapter 14 introduce to ethers, epoxides, and sulfides. After completing this chapter, students will be able to: Draw and name ethers and heterocyclic ethers, including epoxides; explain the trends in their boiling points, solubilities, and solvent properties; determine the structures of ethers from their spectra, and explain their characteristic absorptions and fragmentations;...
The characteristics lines in X-ray
spectra result from electronic
transitions between inner atomic
orbitals. The X-ray spectra for most heavy
elements are much simpler than the
UV/Vis spectra observed in ICP-OES,
for example. (Only a few lines!!!) Big difference between X-ray and UVVis:
The radiation is ionizing, and
doesn’t just excite electrons to higher
levels. Moseley’s law: Predicts the basic
relationship of atom number and the
frequency of the characteristic lines
It is difficult to overemphasize the importance of magnetic resonance techniques in
chemistry. Experimental spectra can usually be successfully interpreted empirically,
but more difficult cases require a prediction based on the electronic structure. In the
last 25 years the calculation of magnetic resonance parameters from first principles
has become a powerful research tool that can significantly enhance the utility of
magnetic resonance techniques when empirical interpretations are insufficient.
The powders of Mg(Al1-xEux)2O4 have been synthesized by sol-gel method. Optical properties of the material were investigated. The nature of lines in luminescence spectra is related to the electron transitions of Eu3+ ions corresponding to different sites in the lattice. The influence of Eu concentration on optical spectra was studied.
Conventional and saturation transfer electron paramagnetic resonance spectroscopy (EPR and ST EPR) was used to study the orientation of probe molecules in muscle ﬁbers in diﬀerent intermediate states of the ATP hydrolysis cycle. A separate procedure was used to obtain ST EPR spectra with precise phase settings even in the case of samples with low spectral intensity. Fibers prepared from rabbit psoas muscle were labeled with isothiocyanate spin labels at the reactive thiol sites of the catalytic domain of myosin....
La0.9Ce0.1Mn0.5Cu0.5O3 was prepared by the combustion method using polyvinyl alcohol (PVA) and corresponding metal nitrates. Samples were characterized by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), FT-IR spectra, transmission electron microscopy (TEM) and BET (Brunaure-Emmet-Teller) measurements. The results show that perovskite phase is formed at 600o C. Sample synthesized under optimal condition has nanostructure with large specific area.
The hole closing reported in this letter is certainly not caused by
deposition of carbon-rich material by the electron beam, a common
phenomenon in electron microscopy. The observation that large pores
expand is in direct contradiction with potential contamination growth.
Secondly, electron-energy-loss spectra (EELS) locally obtained on the
material that filled a nanopore clearly show the presence of silicon and
oxygen,but the absence of any carbon (detection limit was less than 2%).