Thomas Schultz

We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 +/- 10 picoseconds for the near-planar hydrogen-bonded dimer, which is significantly shorter than the lifetime of either the monomer or the 3- and 4-membered no

The excited-state dynamics of trans-azobenzene were investigated by femtosecond time-resolved photoelectron spectroscopy and ab initio molecular dynamics. Two near-degenerate pipi* excited states, S2 and S3,4, were identified in a region hitherto associated with only one excited state. These results help to explain contradictory reports about the photoisomerization mechanism and the wavelength dependence of the quantum yield. A new model for the isomerization mechanism is proposed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIsolation of volatile components from a model systemThomas H. Schultz, Robert A. Flath, T. Richard Mon, Sue B. Eggling, and Roy TeranishiCite this: J. Agric. Food Chem. 1977, 25, 3, 446–449Publication Date (Print):May 1, 1977Publication History Published online1 May 2002Published inissue 1 May 1977https://pubs.acs.org/doi/10.1021/jf60211a038https://doi.org/10.1021/jf60211a038research-articleACS PublicationsRequest reuse permissionsArticle Views894Altme

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPermeability of Pectinate Films to Water Vapor.T. H. Schultz, J. C. Miers, H. S. Owens, and W. D. MaclayCite this: J. Phys. Chem. 1949, 53, 9, 1320–1330Publication Date (Print):September 1, 1949Publication History Published online1 May 2002Published inissue 1 September 1949https://doi.org/10.1021/j150474a002RIGHTS & PERMISSIONSArticle Views166Altmetric-Citations44LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article

Ab initio calculations and femtosecond pump-probe ionization experiments were carried out to identify excited state relaxation processes in isolated thymine monomer and small thymine-water clusters. Three transient species with life times of < or =100 fs, 7 ps and >1 ns were observed in the experiments on gas phase thymine. The longer-lived transients were weak or absent in thymine-water clusters. Available theoretical results on thymine agree with the assignment of low-lying pi-pi* and n-pi* ex

We report [1+1′] picosecond time-resolved pump–probe photoelectron spectra of the UV bands of the allyl radical. The experiments are performed in a molecular beam of allyl radicals, generated by supersonic jet flash pyrolysis. Photoelectron spectroscopy in a magnetic bottle is shown to be a suitable method for investigating the photophysics of organic radicals. Lifetimes were obtained for all vibronic bands between 250 and 238 nm previously assigned by MPI spectroscopy to the electronically exci

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnalysis of orange volatiles with vapor samplingThomas H. Schultz, Robert A. Flath, and T. Richard. MonCite this: J. Agric. Food Chem. 1971, 19, 6, 1060–1065Publication Date (Print):November 1, 1971Publication History Published online1 May 2002Published inissue 1 November 1971https://pubs.acs.org/doi/10.1021/jf60178a019https://doi.org/10.1021/jf60178a019research-articleACS PublicationsRequest reuse permissionsArticle Views122Altmetric-Citations39LEARN

SUMMARY— The organic volatiles in commercial Delicious apple essence were extracted and reduced to an oil by five different extractants: isopentane, diethyl ether, charcoal (with elution by ether), liquid carbon dioxide, and 1,2‐dichloro‐1,1,2,2‐tetrafluoroethane. Identification and quantitative estimation of the maior constituents were made by gas‐liquid chromatography and mass spectrometry. Isopentane and the fluorocarbon were similar in action. Compared with ether they gave lower recoveries,

The nonradiative decay rates of the vibrational ground state and the υ7 fundamental in the electronically excited B 2A1 state of the allyl radical, C3H5, are studied by picosecond time-resolved pump-probe photoelectron spectroscopy. The states decay by internal conversion with a time constant of 20 and 16 ps, respectively.

We report picosecond time-resolved pump-probe photoelectron spectra of the allyl radical, C3H5, and the fully deuterated allyl, C3D5, carried out in order to elucidate the primary photophysical processes upon UV excitation. It is shown that the UV bands of allyl decay in a two-step process: the first step is an internal conversion to the lower-lying A-state within 20 ps or less, while the second step is a very fast decay from the A-state to the electronic ground state through a conical intersect

SUMMARY Volatiles from California Valencia orange juice low in peel oil were removed under vacuum in a Kontro evaporator. The organic constituents were extracted with ether and examined by capillary gas‐liquid chromatography and mass spectrometry in combination. Constituents of relatively high water solubility were found mainly in the first condensers of the essence recovery system, whereas sesquiterpenoids were more prominent in a downstream colder condenser. The major esters of the juice were

Rotational spectra have traditionally been measured without a concurrent means of differentiating the molecular constituents of the sample. Here, we present an all-optical multipulse experiment that allows the correlated measurement of rotational and mass or photoelectron spectra by combining Fourier transform rotational coherence spectroscopy with resonance-enhanced multiphoton ionization. We demonstrate the power of this method with the determination of ground-state rotational constants and fr