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  • 1
    Electronic Resource
    Electronic Resource
    Photodissociation of N2O: J-dependent anisotropy revealed in N2 photofragment images (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 3411-3417 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Photofragment imaging is used to measure the state-specific angular distributions of N2 produced in the ultraviolet photodissociation of N2O. 2+1 REMPI (resonance enhanced multiphoton ionization) through the a″(1Σg+) state is used to ionize individual rotational states of N2(ν=0) between J=40 and J=90 produced when N2O is dissociated by light of approximately 203 nm. The anisotropy parameter, β, used to characterize the angular distributions of the N2 ion images, is greater than one for the lower rotational levels probed, and decreases to approximately zero for the highest rotational levels of N2. The positive beta parameter indicates that the products arise primarily from a parallel transition to the 2 1A′(1Δ) state in the parent molecule, and the decrease in β with increasing J of N2 is due to increased bending in the parent N2O during dissociation. The ion images also allow us to assign transitions in a spectroscopically perturbed region of the N2 photofragment REMPI spectrum and to reveal the production of N2 products in the first vibrationally excited state. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478207
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  • 2
    Electronic Resource
    Electronic Resource
    Photofragment Imaging of Kr2 and ArKr van der Waals Molecules following Two-Photon Excitation (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 17700-17710 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100050a006
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  • 3
    Electronic Resource
    Electronic Resource
    H/D fragment ratio in Lyman-α photolysis of CH2D2 (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 3399-3402 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photofragment imaging technique is used to study the formation of H and D in the photolysis of CH2D2. From the images different reaction channels are distinguished that lead to hydrogen fragments. For the channel that leads to hydrogen atoms concomitant with methyl fragments a H/D ratio of 3.5±0.6 is found. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471045
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  • 4
    Electronic Resource
    Electronic Resource
    Photofragment imaging of methane (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 4019-4030 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photolysis of methane is studied using photofragment imaging techniques. Our study reveals that the photolysis of methane proceeds via many different pathways. The photofragment imaging technique is used to resolve and characterize these various pathways and provides therefore unique insight into the dynamical processes that govern this photodissociation. The formation of H-atom photofragments following absorption of a Lyman-α photon, and H2 photofragments following absorption of two ultraviolet photons (λ=210–230 nm) are studied. The measured H-atom photofragment images reveal that a channel that produces fast H atoms concomitant with methyl fragments is dominant in the Lyman-α photolysis of methane. This channel leads to an anisotropic recoil of the fragments. A secondary channel is observed leading to the formation of somewhat slower H atoms, but an unique identification of this second channel is not possible from the data. At least part of these slower H atoms are formed via a channel that produces H atoms concomitant with CH and H2 photofragments. The recoil of these slower H atoms appears to be isotropic. The measured, state-resolved H2(v,J), photofragment images reveal that two channels lead to H2 photofragments from the two-photon photolysis of methane: a channel that leads to H2 products concomitant with methylene fragments; and a channel that leads to H2 products concomitant with CH and H fragments.H2(v,J) rotational and vibrational distributions are measured for each of these two channels separately. The H2 products formed via the H2+CH2 channel are rotationally and vibrationally highly excited, whereas those formed via the H2+CH+H channel are rotationally and vibrationally cooler. Rotational distributions of H2 formed via the H2+CH+H channel are well reproduced by Boltzmann distributions. Results on D2 elimination following two-photon photolysis of CD4 are in general similar and in qualitative agreement with the results on CH4. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471214
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  • 5
    Electronic Resource
    Electronic Resource
    Translational energy-resolved collisionally activated methyl cation transfer from protonated methane to argon, krypton, and xenon and from protonated fluoromethane to argon and molecular oxygen (1992)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 96 (1992), S. 8870-8876 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100201a035
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  • 6
    Electronic Resource
    Electronic Resource
    Metabolic labeling of C. elegans and D. melanogaster for quantitative proteomics (2003)
    [s.l.] : Nature Publishing Group
    Nature biotechnology 21 (2003), S. 927-931 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] A crucial issue in comparative proteomics is the accurate quantification of differences in protein expression levels. To achieve this, several methods have been developed in which proteins are labeled with stable isotopes either in vivo via metabolic labeling or in vitro by protein derivatization. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt848
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  • 7
    Electronic Resource
    Electronic Resource
    A high-quality catalog of the Drosophila melanogaster proteome (2007)
    [s.l.] : Nature Publishing Group
    Nature biotechnology 25 (2007), S. 576-583 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Understanding how proteins and their complex interaction networks convert the genomic information into a dynamic living organism is a fundamental challenge in biological sciences. As an important step towards understanding the systems biology of a complex eukaryote, we cataloged 63% of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt1300
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of Glyoxalase I (E. coli)—Inhibitor Interactions by Electrospray Time-of-Flight Mass Spectrometry and Enzyme Kinetic Analysis (2000)
    Springer
    The protein journal 19 (2000), S. 389-397 
    Details
    ISSN: 1573-4943
    Keywords: Glyoxalase I ; bioaffinity mass spectrometry ; noncovalent interactions ; inhibitor screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Potential inhibitors of the enzyme glyoxalase I from Escherichia coli have been evaluated using a combination of electrospray mass spectrometry and conventional kinetic analysis. An 11-membered library of potential inhibitors included a glutathione analogue resembling the transition-state intermediate in the glyoxalase I catalysis, several alkyl-glutathione, and one flavonoid. The E. coli glyoxalase I quaternary structure was found to be predominantly dimeric, as is the homologous human glyoxalase I. Binding studies by electrospray revealed that inhibitors bind exclusively to the dimeric form of glyoxalase I. Two specific binding sites were observed per dimer. The transition-state analogue was found to have the highest binding affinity, followed by a newly identified inhibitor; S-{2-[3-hexyloxybenzoyl]-vinyl}glutathione. Kinetic analysis confirmed that the order of affinity established by mass spectrometry could be correlated to inhibitory effects on the enzymatic reaction. This study shows that selective inhibitors may exist for the E. coli homologue of the glyoxalase I enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026439531005
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  • 9
    Electronic Resource
    Electronic Resource
    Mass-specific selection of ions in Fourier-transform ion cyclotron resonance mass spectrometry. Unintentional off-resonance cyclotron excitation of selected ions (1991)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 406-414 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Mass-specific selection of ions in Fourier-transform ion cyclotron resonance (FT-ICR) ion trap is shown to be hampered by unavoidable off-resonance cyclotron exctron excitation of the ions to be selected. This unintentional off-resonance cyclotron excitation is caused by radio-frequency fields which are applied during the selection procedure to eject unwanted ions by on-resonance excitationof their cyclotron motion. The experimental results indicate that the effective cyclotron motion of the ions subjected to an off-resonance single-frequency RF field is alternatingly excited and de-excited with a periodicity equal to 2π/(ω0-ωeff), where ω0is the frequency of the excitation field and ωeff is the effective ion cyclotron frequency. Furthermore, it has been demonstrated that the translational energy gained during off-resonance cyclotron excitation can be predicted quantitatively by theory. The net translational energy can be minimized below 1 eV if the duration of the individual single-rfrequency excitation fields is set to k2π/(ω0-ωeff), where k has to be an integer, representing the number of full off-resonance excitation/de-excitation periods. The unintentional off-resonance cyclotron excitation is shown to lead to an instrumental upper limit for the mass selectivity of ion selection, the so-called front-end resolution. This upper limit is proportional to the cell diameter, and the square of the magnetic field strength, and inversely proportional to the noise level of the excitation RF-field, and the mass of the ions to be selected. It is demonstrated that an instrumentally dictated maximum mass resolution of better than 50000 can be obtained for the selection of ions with a nominal mass-to-charge ratio of 79.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290050907
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  • 10
    Electronic Resource
    Electronic Resource
    Gas-phase bimolecular chemistry of isomeric cyclic ethylenehalonium and α-haloethyl cationsDedicated to Professor H. Budzikiewicz on the occasion of his 60th birthday. (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 235-244 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase bimolecular chemistry of C2H4X+ (X = F, Cl, Br) cations was studied using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The results support earlier suggestions that at least two isomers of the halonium ions C2H4X+ (X = Cl, Br) exist, but no experimental evidence was found for the possibility of more than one stable isomer for C2H4F+. It is shown that the cyclic ethylenehalonium and α-haloethyl cations react differently with various substrates. The probe reactions used to characterize the two isomers were hydrogen-deuterium exchange with deuterium oxide and reactions with benzene, alkenes and vinyl ethers. It was found that the α-haloethyl cations react as proton donors and/or electrophiles, whereas the cyclic ethylene-chloronium and ethylenebromonium ions react as electrophile and/or as haloganyl cation donors in reactions with alkenes and vinyl ethers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280316
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