Extended Diaryl Diselenide Radical Cations in Pentasil Zeolite Studied by EPR and Diffuse Reflectance Optical Spectroscopy

1999 ◽  
Vol 103 (37) ◽  
pp. 7381-7384 ◽  
Author(s):  
Prasad S. Lakkaraju ◽  
Kui Shen ◽  
Heinz D. Roth ◽  
Hermenegildo García
Keyword(s):  
Optical Spectroscopy ◽  
Diffuse Reflectance ◽  
Radical Cations ◽  
Pentasil Zeolite

In Vivo Optical Spectroscopy Detects Radiation Damage in Brain Tissue

Neurosurgery ◽  
2005 ◽  
Vol 57 (3) ◽  
pp. 518-525 ◽  
Author(s):  
Wei-Chiang Lin ◽  
Anita Mahadevan-Jansen ◽  
Mahlon D. Johnson ◽  
Robert J. Weil ◽  
Steven A. Toms
Keyword(s):  
Radiation Damage ◽  
Optical Spectroscopy ◽  
Diffuse Reflectance ◽  
Radiation Injury ◽  
Hippocampal Sclerosis ◽  
Spectral Feature ◽  
Recurrent Tumor ◽  
Previous Irradiation ◽  
Brain Tissues

ABSTRACT OBJECTIVE: Magnetic resonance imaging abnormalities in malignant brain tumors after irradiation may represent either recurrent tumor or radiation injury. Optical spectroscopy may represent a novel technique to identify radiation damage in brain tissues and to differentiate contrast-enhancing lesions from recurrent tumor. METHODS: Fluorescence and diffuse reflectance spectra were acquired from 90 patients: 15 undergoing surgical resection for presumed recurrent tumor after radiation therapy, 15 with epilepsy and hippocampal sclerosis, and 60 with tumors who had not received irradiation. Optical spectra were acquired from 6 to 10 sites and were compared with a biopsy obtained from beneath the optical spectroscopy probe; the data then were classified by a neuropathologist blinded to the spectroscopy data. A probe for the intraoperative collection of diffuse reflectance and fluorescence spectra was used. RESULTS: Thirteen of 15 patients (29 of 129 spectra) with previous irradiation showed a unique spectral feature characterized by a fluorescence peak centered at 500 nm (F500). All biopsy specimens showing histopathological signs of radiation injury had the F500 on their corresponding spectra (18 of 18). The F500 was identified in another 10% (11 of 111 spectra) of samples with previous irradiation but no histologically identifiable signs of radiation damage. The F500 was never seen in the normal temporal lobe of epilepsy patients with hippocampal sclerosis (0 of 105) and was seen in only 1.5% of tumor patients who did not undergo previous irradiation (6 of 433). CONCLUSION: Optical spectroscopy detects radiation damage in brain tissues. The F500 spectral peak may allow accurate selection of tissues for biopsy in evaluating patients with new, contrast-enhancing lesions in the setting of previous irradiation.

Roughness Characterization by Optical Spectroscopy of CoSi2 Thin Films

1996 ◽  
Vol 440 ◽  
Author(s):  
S. Bocelli ◽  
G. Guizzetti ◽  
F. Marabelli ◽  
S. Hatziconstantinidou ◽  
C.S. Petersson
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Optical Properties ◽  
Surface Quality ◽  
Optical Spectroscopy ◽  
Spectroscopic Ellipsometry ◽  
Diffuse Reflectance ◽  
Growth Technique

AbstractSpecular and diffuse reflectance and spectroscopic ellipsometry were used to characterize a series of Cosi2 films obtained by heat treatment on a Co/Ti bilayer. The surface quality is strongly affected by etching procedures. The intrinsic optical properties of the CoSi2 film exhibit a small dependence on the growth technique.

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

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