Mehdi Dehghany

Abstract: A new parallel

K=0 band of the cyclic CO2 trimer is observed at 2364 cm−1. The trimers are generated in a pulsed supersonic expansion from a slit-jet nozzle and probed with a tunable infrared diode laser. The band is assigned as a combination of an intramolecular CO2 monomer 3 stretch and an intermolecular out-of-plane torsion, giving a torsional frequency of 12–13 cm−1. The band is surprisingly strong and completely unperturbed, providing a rare and near perfect example for a parallel band of a symmetric top molecule with C3h symmetry and zero nuclear spins. © 2008 American Institute of Physics. DOI: 10.1063/1.2834931

Abstract: Dental caries is the leading cause of tooth loss, which can promptly be prevented if detected in early stages of progression. Unfortunately, conventional diagnostic modalities currently used in dentistry lack the sensitivity to detect early caries. The authors' intention is to compare the ability of polarized Raman spectroscopy and thermophotonic imaging to make early caries diagnosis. Extracted human teeth with no visible stain or defects were artificially demineralized in accordance to a well-known protocol in dentistry for simulated early caries development at several demineralization stages. Samples were then inspected using polarized Raman spectroscopy and thermophotonic imaging. The sensitivities of these two diagnostic modalities are compared, and the results are verified using transverse micro-radiography. It was found that compared to polarized Raman spectroscopy, thermophotonic imaging exhibits superior sensitivity to very early stages of demineralization.