David D. Saperstein

Fluorescence quenching of ultraviolet excited aromatic solutions by chloroform and several related chlorinated methanes

Relative fluorescence quenching rate constants for solvent excitation to S1, S2, and S3 are reported for a number of the solvent–quencher (S–Q) systems in which the solvent was either benzene, toluene, o‐xylene, p‐xylene, or anisole and the quencher was either CH2Cl2, CHCl3, CDCl3, CH3CCl3, CFCl3, or CCl4. The magnitude of the experimental rate constants are found to follow qualitatively, but not quantitatively, the hypothesis that the rate‐determining step in the quenching process is the formation of a DSAQ (donor–acceptor) exciplex by an excited solvent molecule (Sn, n=1, 2, or 3) and a quencher molecule. Tentative explanations are offered for these findings.

Blood plasma investigations by resonance raman spectroscopy: Detection of carotenoid pigments

Using Raman spectroscopy, we demonstrate that low levels of β-carotene, lycopene, and xanthophyll give rise to resonance enhanced bands in blood plasma. These results explain the significance of previously unidentified spectral maxima which have been related to the state of health of the blood donor.

Fourier transform infrared analysis of the ammoxidation of 4-methylthiazole over a metal oxide catalyst

The gaseous products of the reaction of 4-methylthiazole (4-MT), air, 14NH3, and 15NH3 have been analyzed by on-line Fourier transform infrared spectroscopy. The products observed, including those due to partial and full oxidation, account for 95 to 98% of the starting 4-MT. Estimates of the activation energy (20 kcal/mol) and the excess heat due to combustion (350 kcal/mol/mol of 4-MT combusted) have been calculated. In addition, we have observed an unexpected reaction that is formally bimolecular in 4-MT.

On-Line Infrared (IR) Spectral Interpretation Of Organic Compounds Using A Fourier Transform (FT) Sized Minicomputer

There are now several commercially available computer routines for identifying unknowns by a spectral search and match procedure. These routines work well if the match is perfect, however they can be frustrating when the data base does not contain the unknown as one of its entries. An alternative method for identifying an unknown is to establish the IR active funtionalities that are presnt. This can be done by a classification-matching method or by an interpretation method that tries to mimic how the chemist/spectroscopist thinks. The latter has been discussed in several papers and forms the starting point for our studies.