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Topic: Rotational spectroscopy

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In the News (Tue 18 Jun 19)

  Rotational spectroscopy - Definition, explanation
Rotational spectroscopy studies the absorption of electromagnetic radiation (typically in the microwave region of the spectrum) by molecules.
Rotational spectroscopy is only really practical in the gas phase where the rotational motion is quantized.
For a molecule to have a rotational spectrum it is necessary (to first order) that it have a dipole moment, that is a difference between the center of charge and the center of mass, or equivalently a separation between two unlike charges.
www.calsky.com /lexikon/en/txt/r/ro/rotational_spectroscopy.php   (1380 words)

  Rotational spectroscopy - Wikipedia, the free encyclopedia
Rotational spectroscopy or microwave spectroscopy studies the absorption and emission of electromagnetic radiation (typically in the microwave region of the electromagnetic spectrum) by molecules associated with a corresponding change in the rotational quantum number of the molecule.
Rotational spectroscopy is only really practical in the gas phase where the rotational motion is quantized.
Rotational spectrum from a molecule (to first order) requires that the molecule have a dipole moment, that is a difference between the center of charge and the center of mass, or equivalently a separation between two unlike charges.
en.wikipedia.org /wiki/Rotational_spectroscopy   (1777 words)

 JPL Molecular Spectroscopy
Molecular spectroscopy is the study of absorption of light by molecules.
In the gas phase at low pressures, molecules exhibit absorption in narrow lines which are very characteristic of the molecule as well as the temperature and pressure of its environment.
In the microwave and long-wavelength infrared regions of the spectrum, these lines are due to quantized rotational motion of the molecule.
spec.jpl.nasa.gov   (695 words)

 Experiment 9. Rotational-Vibrational Spectroscopy. Introduction
The rigid rotor model may be used to approximate the rotational contribution to the IR spectrum of a diatomic molecule.
The last term accounts for the interaction between the vibration and rotation of the molecule; as the molecule vibrates, the moment of inertia changes and the rotation of the molecule is affected.
Since the reduced mass affects the vibrational and rotational behavior or a molecule, the energy of its transitions are affected.
www.chemistry.nmsu.edu /studntres/chem435/Lab9/intro.html   (3215 words)

 High Resolution Molecular Spectroscopy Group: Research Topics
The study of rotational spectra of molecular ions is of particular interest in relation to a possible detection of these species in the interstellar medium by radioastronomers.
Rotational spectra of HN, and SH were studied in our laboratory.
High-resolution infrared spectra and rotational spectra in excited vibrational states yield useful information for the calculation of equilibrium structures, harmonic and anharmonic force fields.
www.ciam.unibo.it /gcazzoli/temi_eng.html   (404 words)

 [No title]   (Site not responding. Last check: 2007-10-11)
The energy and orientation of a molecule's tumbling motion is decribed as a rotational state.
The distribution of molecules among rotational states gives clues about the density and temperature of the gas.
The intensities of the spectral lines are a measure of the number of molecules in each rotational state.
dsnra.jpl.nasa.gov /IMS/simple.html   (916 words)

 Department of Chemistry at the University of Virginia
We have developed a new type of molecular spectroscopy called dynamic rotational spectroscopy to study isomerization reactions of isolated molecules.
The basis of rotational (or microwave) spectroscopy is that the geometry determines the measured rotational frequencies.
The Rotational Spectra of Single Molecular Eigenstates of 2- fluoroethanol: Measurement of the Conformational Isomerization Rate at 2980 cm-1.
www.virginia.edu /chem/people/faculty/pate   (761 words)

 [No title]
Rotational spectroscopy is especially suited for averaging and leads to extensive information about molecules like structure, dipole moment, nuclear quadrupole coupling constants and potential barriers.
The rotational spectrum of a molecule of this type is dominated by the three principal inertial moments of the molecule as a rotating body.
Nonetheless, this method can usually not take full advantage of the very high precision of microwave spectroscopy, because the inertial moments taken from the spectra are contaminated by a multitude of small but unknown interactions between molecular rotation and vibration, even in the vibrational ground state of the molecule.
www.uni-ulm.de /uni/veroeff/fb/93-95/12.html.en   (1701 words)

 Oka Ion Factory - Oka Publications
Infrared spectroscopy of short-lived molecules: Observation of the ν
Rotational spectroscopy of molecular ions using diode lasers, D.-J. Liu, W.-C. Ho, and T. Oka, J.
Infrared spectroscopy of molecular ions, T. Oka in “Frontiers of Laser Spectroscopy of Gases” (A. Alves, J. Brown, and J. Hollas, Eds.), pp.
fermi.uchicago.edu /publications/cv.shtml   (4201 words)

 Vibrational spectroscopy - Wikipedia, the free encyclopedia
The vibrational states of a molecule can be probed in a variety of ways.
The most direct way is infrared spectroscopy because vibrational transitions typically require an amount of energy that corresponds to the infrared region of the spectrum.
However, Raman spectroscopy, vibrational circular dichroism and electron energy loss spectroscopy also provide vibrational information.
en.wikipedia.org /wiki/Vibrational_spectroscopy   (90 words)

 Chemistry 3 Course Web Site - Lectures   (Site not responding. Last check: 2007-10-11)
You should have a detailed knowledge and understanding of the factors which determine the energies, intensities and linewidths of the transitions observed in molecular rotation, vibrational and electronic spectra.
You should be able to derive, from rotational spectroscopic data, the rotational constant, moment of inertia and bond length of a diatomic molecule, and to relate electron diffraction radial distribution curves to molecular structures.
You should be able to derive, from vibrational spectroscopic data, the vibrational wavenumber, anharmonicity constant and dissociation energy of a diatomic molecule.
www.chem.ed.ac.uk /teaching/undergrad/chemistry3/lectures/g1t1_ms.html   (179 words)

 Cobolt AB
Spectroscopy can be summarised as the study of the interaction between light and matter.
In particular, Raman spectroscopy yields unique information by investigating the vibrational and rotational modes of the molecule.
Narrow spectral bandwidth, spectral purity and a high level of wavelength stability are important features for this application.
www.cobolt.se /applications_raman_spectroscopy.php   (121 words)

 QUT | Science | Publications   (Site not responding. Last check: 2007-10-11)
Legon, J. Thumwood and E. Waclawik, “The Interaction of Water and Dibromine in the Gas Phase: An Investigation of the Complex H 2 O···Br 2 by Rotational Spectroscopy and Ab Initio Calculations” Chem.
Legon, J. Thumwood and E. Waclawik, “Rotational spectroscopy of H 3 P···BrCl and the systematics of intermolecular electron transfer in the series B···BrCl, where B = CO, HCN, H 2 O, C 2 H 2, C 2 H 4, H 2 S, NH 3 and PH 3 ” J.
Waclawik and A. Legon, "Halogen nuclear quadrupole coupling in the rotational spectrum of H 3 N···ICl as a probe of inter- and intramolecular electron transfer" Phys.
www.sci.qut.edu.au /profiles/waclawik/publications.jsp   (897 words)

 Amazon.com: Modern Spectroscopy: Books: J. Michael Hollas   (Site not responding. Last check: 2007-10-11)
Michael Hollas "Spectroscopy is basically an experimental subject and is concerned with the absorption, emission or scattering of electromagnetic radiation by atoms or molecules..." (more)
The latest edition of this highly acclaimed title introduces the reader to a wide range of spectroscopies, and includes both the background theory and applications to structure determination and chemical analysis.  It covers rotational, vibrational, electronic, photoelectron and Auger spectroscopy, as well as EXAFs and the theory of lasers and laser spectroscopy.
Spectroscopy is basically an experimental subject and is concerned with the absorption, emission or scattering of electromagnetic radiation by atoms or molecules.
www.amazon.com /exec/obidos/tg/detail/-/0470844167?v=glance   (844 words)

 Kent State University -- Mike Tubergen
Sample is admitted into the spectrometer by a supersonic expansion of argon which both cools the molecules to ~5 K (rotational temperature) and isolates molecules from neighbors—eliminating the possibility that interactions between molecules might distort the conformational structure.
The frequency of the signal is equal to the frequency of the rotational transition; a Fourier-transform converts the oscillating signal into a spectrum as a function of frequency.
By measuring rotational transitions, we are able to determine molecular moments of inertia and ultimately determine the bond distances and angles.
dept.kent.edu /chemistry/Faculty/Research/tubergen.htm   (684 words)

 PhD Research of Juliane L. Fry   (Site not responding. Last check: 2007-10-11)
We have studied the kinetics and vibrational spectroscopy of peroxynitrous acid (HOONO) in the region of the first OH stretch overtone experimentally and theoretically, using action spectroscopy and cavity ringdown spectroscopy, and statistical master equation and two-dimensional coupled OH stretch torsion theoretical models.
The complex spectroscopy of the cis-cis HOONO first OH overtone region is then elucidated using a two-dimensional OH stretch torsion coupling model, which accurately predicts the major features in both the absorption and action spectra of cis-cis HOONO.
The action spectroscopy technique gains its high sensitivity by employing laser induced fluorescence detection of OH photofragments of HOONO dissociation, after energy has been resonantly coupled into the molecule via a vibrational mode.
www.gps.caltech.edu /~fry/phd/phd.html   (1420 words)

 Introduction to High Resolution Spectroscopy - Microwave spectrum of a rigid-rotor diatomic
In microwave spectroscopy, rotational transitions are allowed between adjacent J levels - the selection rule is:
If one level has a rotational quantum number of J then absorption is to the level with quantum number J+1.
Once you have covered all of the available resources for rotational spectroscopy, you should test your knowledge and understanding with the self test.
www.hull.ac.uk /chemistry/spectroscopy/rigid_rotor_energy_difference.php?res=   (154 words)

 Laszlo Nemes   (Site not responding. Last check: 2007-10-11)
His specialization is in molecular spectroscopy in which field he held several grants and traveled wide to do research abroad.
His main topics to pursue in spectroscopy were normal coordinate analysis of polyatomics, vibrational-rotational analysis of high-resolution gas-phase infrared spectra, microwave rotational spectroscopy of small molecules, various laser spectroscopic methods for small molecules and recently ultraviolet and visible diatomic emission spectroscopy from laser-induced carbon plasmas.
He has also done gas-phase emission IR spectroscopy on C60 and C70 and theoretical work on fullerenes, including symmetry analysis of the vibrational potential function, and vscf calculations on the anharmonicity of C60 vibrations.
www.chemistry.emory.edu /faculty/bowman/group/laszlo   (249 words)

The book reviews the results of vibration—rotational spectroscopy of molecules obtained recently by combining modern computational methods of quantum chemistry with the new techniques of high-resolution rotational and vibration—rotational spectroscopy.
It shows for example that the tunneling vibration—rotational spectroscopy of the van der Waals complexes provides a new look at intermolecular forces while the high precision and sensitivity of the submillimeter-wave and Fourier transform microwave spectroscopy make it possible to study complex rotational spectra of molecules in excited vibrational states.
New results of high level ab initio quantum chemical computations of vibrational and rotational energy levels and dipole moment functions of unusual molecules will be discussed together with the recent discovery of clustering of energy levels in asymmetric tops.
www.worldscibooks.com /chemistry/2242.html   (321 words)

 Zwier Group Home Page   (Site not responding. Last check: 2007-10-11)
However, because the rotational wavefunction remains bound at all energies below the dissociation threshold in the ground electronic state, the rotational spectral features remain sharp.
We are currently involved in studying the rotational dynamics of intermediate sized molecules (~ 10 atoms) in the 3300-6550 cm-1 energy region using a combination of infrared laser spectroscopy and Fourier-Transform microwave techniques.
From the rotational spectrum we can obtain information on the rate of free rotation in the rotor coordinates and the effects this process has on reorienting the molecular frame.
www.chem.purdue.edu /zwier/past.html   (2083 words)

 Douglas T. Petkie
High-resolution millimeter and submillimeter-wave spectroscopy of fundamental molecules of atmospheric and interstellar interest.
Rotational Spectroscopy and Infrared Band Simulations of Nitric Acid and Chlorine Nitrate.
Rotational Spectra of the Excited Vibrational State of Nitric Acid.
www.wright.edu /~doug.petkie/research.htm   (350 words)

Characterisation of a Pre-reactive Intermediate in Gas-phase Mixtures of Fluorine and Ammonia: the Rotational Spectrum of the H
Pre-reactive Intermediates in Mixtures of Hydrocarbons with Chlorine Monofluoride: Characterisation of Ethyne.....ClF and Ethene....ClF by Rotational Spectroscopy.
Rotational Spectroscopy of a Pre-reactive Mixture of H
www.le.ac.uk /chemistry/egh1/fluorine/pub2pap~95-99.html   (1190 words)

 [No title]   (Site not responding. Last check: 2007-10-11)
We can find the rotational constant for the excited vibrational state by taking the difference of specific spectral lines to remove the influence of the rotation of the ground vibrational state.
Polyatomic Vibrational Spectroscopy Normal Vibrational Modes Vibrations in a polyatomic molecule involve movement of all the atoms in a molecule.
The applied electric field deforms the electron cloud and the effect of the deformation is proportional to the strength of the applied electric field.
www.unomaha.edu /tiskochem/Chem3360/Lecture_Notes/Word_Files/Vibrational_Spectroscopy.doc   (1889 words)

 Undergraduate research students
Her work on 3-butyn-1-ol was included in a manuscript on the rotational spectrum and ab initio calculations on this molecule (this paper appeared in the Journal of Molecular Structure in May 2004).
Rotational Spectrum, Structure and Modeling of the OCS-CS van der Waals Dimer, J.J. Newby, M.M. Serafin, R.A. Peebles, S.A. Peebles, Phys.
Heavy atom structure and conformer stabilities of cyclopropyl carbinol from rotational spectroscopy and ab initio calculations, J.J. Newby, R.A. Peebles, S.A. Peebles, J.
www.ux1.eiu.edu /~cfsap/Undergrads.htm   (855 words)

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