Magnetic circular dichroism measurement

Several theoretical studies concluded that the two bands originate from electronic transitions from one ground state to two excited states [47-51,55], The D3-symmetry conformation was confirmed by an X-ray diffraction study of crystal samples [56], resonance Raman studies [46,51,57], and magnetic circular dichroism measurements [55], Yet, no C2-symmetry conformation has been identified yet. 

Another important property is polarization. SR is plane polarized when viewed in the plane of the particle trajectory and elliptically polarized above or below this plane. The polarization is of crucial importance to the study of the spatial distribution and spin of the ejected photoelectrons, and to VUV magnetic circular dichroism measurements. 

Differences between the two sets of pairs of the four isomeric purine types also arise from magnetic circular dichroism measurements of the four A/ methylpurines (73JHC419). Thus the MCD bands for the 1-Me and 3-Me forms are of lower intensity and occur at shorter wavelengths than the related bands for the 7-Me and 9-Me isomers. Also protonation results in wavelength shifts and changes in peak intensities and these variations could be used to characterize a particular isomer. Thus peak heights of the bands for the 1-Me and 3-Me isomers after protonation increase by 0.25 and three times whereas those for the 7-Me and 9-Me isomers decrease by 0.25 and three times, respectively. 

Suryanarayanan et al. (1970) have shown that YbSe thin films have two fee phases one stoichiometric as YbSe with a = 5.93 A and the other rich in Se as YbSei.5 with a = 5.65 A. By optical absorption and magnetic circular dichroism measurements they conclude that YbSe is diamagnetic (as YbTe) and YhSe is paramagnetic with a trivalent state for Yb. The optical absorption shows that the transition in YbSe and YbTe can be attributed to ... 

Snyder, P. A., Atanasova, S., 8c Hansen, R. W. C. (2004). Ethylene. Experimental evidence for new assignments of electronic transitions in the n 71 energy region. Absorption and magnetic circular dichroism measurements with synchrotron radiation. Journal of Physical Chemistry A, 10, 4194. 

Infrared, nuclear magnetic resonance, ultraviolet, optical rotary dispersion and circular dichroism measurements have been used for the spectral analysis of thiiranes. A few steroidal thiiranes have been reported to possess infrared absorption in the range from 580 to 700 cm The intermediate thiocyanate derivatives (RSCN) have a strong sharp peak at 2130-2160 cm the isomeric isothiocyanate (RNCS) shows a much stronger but broad band at 2040-2180 cm. ... 

In a few instances the technique of magnetic circular dichroism (MCD) spectroscopy has been used to corroborate assignments based on UV-visible spectroscopy. For example, the assignment of the intense 360 nm band for [S,N,Y to a r (2e") r (2a2") (HOMO LUMO) excitation has been confirmed by the measurement of the MCD spectrum of The MCD spectrum of [S4N3] indicates that each of the... 

Data on the protonation sites for a variety of azaindolizines have been summarized in the previous survey (76AHCS1, p. 536).Tlie measured magnetic circular dichroism spectra for 14 azaindolizines confirmed with some corrections the protonation sites of polyazaheterocycles previously reported and also established the conjugated acid structures of additional compounds (85JOC302).Tlie data are summarized in Scheme 1. 

Compounds 1,2,3,5,10,11,12,13,14 were dissolved in EPIP (diethyl ether, petroleum ether, isopropanol 5 5 2)whereas compounds 4,6,7,8,9,15 were dissolved in THF-DE (tetrahydrofurane, diethyl ether 1 1). These solvent mixtures can be frozen as glassy samples at 77 K. The absorption spectra were recorded on a standard spectrophotometer SF-10 or Beckman-5270. The measurements of fluorescence excitation and emission spectra were made with the aid of a spectrofluorometer SLM-4800 with automatic correction of spectral response. Fluorescence lifetimes were measured with the aid of a pulse fluorometer PRA-3000. Magnetic circular dichroism (MCD) measurements were carried out in a 8 kG magnetic field using a JASCO J-20 circular dichrometer. Triplet state formation was observed for investigated compounds at the experimental set up, whose detailed description can be found in our paper (27). The optical experiments were carried out with a porphyrin concentration of 4.10- - 4.10 mol.l". In NMR investigations (Bruker WM-360) we used higher concentrations ( 5.10" raol.l ) and dried solvents (CDCl, C 2 and toluene-d0). 

The observation of natural ORD or CD requires lack of symmetry in the molecule, but any molecule may exhibit magnetic circular dichroism (MCD). It constitutes a molecular analogy for the Zeeman effect in atomic spectra. Measurements in this area may well reveal substituent interactions which are masked in normal UV spectra. Extensive definitive papers of great interest which well illustrate this have appeared on MCD of pyridine derivatives, measured in cyclohexane, acetonitrile, and alcohol or aqueous acidic solutions for protonated... 

The UV and magnetic circular dichroism spectra of mesoionic pyrido[2,l-b][l,3]oxazine (16, R = CH2Ph) were measured in acetonitrile (85JOC5050). UV spectra of hexahydro[l,3]oxazino[3,2-a]isoquinolines (17) indicated that the ring form (17R) was present in cyclohexane... 

The magnetic circular dichroism spectrum of thioxanthone and the circular dichroism spectrum of its inclusion complex with cyclodextrin have been measured and interpreted with the aid of PPP and CNDO/S calculations. The first jtJt state exhibits intramolecular charge transfer characteristics <1994JPC10432>. 

Resonance Energies. Resonance energies and the like have been calculated by various procedures for 1,5- and other naphthyridines.209,676,812,840 Ultraviolet and Visible Spectra. As well as those obtained from solution, such spectra of 1,5-naphthyridine have been measured in the vapor state830,1119 and the solid state.1094 Interpretation of the various bands has been proposed with assistance from magnetic circular dichroism data1153 and other sources.1016,1113,1336 Several types of calculation have been used to rationa-... 

Measurements. The absorption, circular dichroism (CD), and ESR spectra were recorded with a Hitachi 323 spectrophotometer, a JASCO MOE-1 magnetic circular dichroism spectrometer, and a JEOL JES-FE3X ESR spectrometer, respectively. The measurements of the spectra were carried out at 15°-20°C except for the ESR spectra, which were recorded at 77 K. The resonance Raman spectra were recorded at 10°C with 488.0-nm excitation (Ar+ laser) on a JEOL JRS-400D-002 spectrophotometer. The concentration of copper was determined to be 4.9mM by atomic absorption measured by a Nippon Jarrell-Ash AA-1 spectrometer. 

X-Band ESR spectra were obtained at 77 and 293 K with a JES-FE-3X spectrometer. The g-values were determined relative to Li-TCNQ(g = 2.0026) and the magnetic fields were calibrated by the splitting of Mn(II) in MgO(AH3 4 = 86.9 G). Magnetic circular dichroism (MCD) measurements, using a 11.7-kG magnet, were carried out on a Jasco J-20 spectro-polarimeter and are expressed in terms of molecular ellipticity, [0] = 2.303 (4500/7r) ( - r), with units of (deg cm2)/d mol. 

---