Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Collisional relaxation of H2CO (A˜ 1A2, v4=1, JKa ,Kc=132,12) by He, Ar, Xe, and N2 (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1008-1011 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The collision-induced deactivation of H2CO in a specific rotational level in its first electronically excited singlet state, A˜ 1A2, v4=1, JKa,Kc=132,12, has been investigated with a series of colliders, M=He, Ar, Xe, and N2. The target level was populated via the transition A˜←X˜, 410, 132,12←133,11 using a pulsed dye laser. The subsequent relaxation was monitored using the technique of transient gain spectroscopy (TGS) via the transition A˜→X˜, 201301414, 132,12→131,13, which coincides with the line of an Ar+ laser at λ=488.0 nm. The experiments yielded the overall collisional depopulation rate constants (velocity averaged cross sections) for He, Ar, Xe, and N2, respectively: (5.25±0.20)×10−10 cm3/molecule s (39 A(ring)2), (5.22±0.18)×10−10 cm3/molecule s (86 A(ring)2), (5.37±0.29)×10−10 cm3/molecule s (106 A(ring)2), (8.25±0.29)×10−10 cm3/molecule s (125 A(ring)2), where the uncertainties correspond to the 2σ standard deviations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457224
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Polarization-detected transient gain studies of relaxation processes in v4=1 A˜ 1A2 formaldehyde-h2 (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 4819-4833 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Polarization-detected transient gain spectroscopy (PTGS), a time-resolved PUMP/PROBE scheme with single rotation–vibration level selectivity in both preparative and monitoring stages, has been used to study total depopulation and rotational state-to-state rates in the H2CO A˜ 1A2 v4=1 vibrational level. For H2CO(A˜)/H2CO(X˜) collisions, single rovibronic level depopulation rates in the range 88±2 to 127±6 μs−1 Torr−1 (∼10 times faster than the hard sphere gas kinetic rate) were obtained from Stern–Volmer plots which were found to be linear over at least the 0.02–0.2 Torr pressure region. Rotational relaxation between the 50,5 and 60,6 eigenstates reflects a-dipole propensity rules with the sum of first order ΔJ=+1 and ΔJ=−1 processes accounting for well over 50% of the total removal cross section measured for a single rovibronic level. The agreement between collisional decay rates for the 132,12 eigenstate measured previously by the TGS technique and here by PTGS, 110±3 and 106±4 μs−1 Torr−1, respectively, suggests that elastic reorientation processes (ΔJ=ΔKa =ΔKc =0, ΔM≠0) occur with much less efficiency than inelastic energy transfer. Collisional depopulation from single rotational levels of H2CO A˜ 1A2 v4=1 is a remarkably efficient process, but completely understandable in the small molecule, isolated binary collision limit. None of the multiexponential decay and nonlinear Stern–Volmer effects manifest in previous undispersed fluorescence studies remain when PTGS is used to populate and monitor a single rovibronic level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454694
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Collisional energy transfer in highly vibrationally excited H2CO(X˜ 1A1) (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 1895-1897 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Collisional energy transfer has been investigated in highly vibrationally excited H2CO (X˜ 1A1) at Evib≅11 400 cm−1 using the method of stimulated emission pumping–transient absorption spectroscopy (SEP-TAS). Total depopulation and state-to-state rate constants were measured for several rotational levels of the 2444 vibrational state. For H2CO self-relaxation the depopulation rate constant of the 61,5 level was measured to be k0=(3.12±0.13)×10−9 cm3/molecule s. An analysis of the state-to-state data with a simplified master equation approach yielded rate constants k1=(7.7±1.2)×10−10, k2=(1.2±0.3)×10−10, and k3=(0.6±0.3)×10−10 cm3/molecule s for collisions with ΔJ=1, 2, and 3, respectively, and ΔKa=0, ΔKc=ΔJ, the reverse rate constants being given by microscopic reversibility. Thus, the ΔJ=±1 steps account for ∼50% of all inelastic collisions, which can be rationalized in terms of a simple dipole–dipole interaction. At Evib≅11 400 cm−1, where ρvib≅0.42/cm−1, collisions seem to conserve the vibrational character in spite of the fact that the energy gap between adjacent vibrational states is a fraction of the transferred rotational energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Wood mice (Apodemus sylvaticus L.) as pioneers of recolonization in a reclaimed area (1993)
    Springer
    Oecologia 94 (1993), S. 120-127 
    Details
    ISSN: 1432-1939
    Keywords: Wood mice ; Recolonization ; Population dynamics ; Spacing behaviour ; Feeding habits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A population of wood mice, Apodemus sylvaticus, was studied by live-trapping for 15 months in an area recently reclaimed from lignite open-mining, where the species is a pioneer of recolonization. Population dynamics, spacing behaviour and feeding habits were compared with data in the literature in order to investigate how these characteristics were affected by the peculiar habitat conditions and the special situation of early colonization. Population density was remarkably high with a peak of 86 individuals/ha in autumn and a low of 20 individuals/ha in late spring. The sex-ratio was always biased towards males except during periods of low density, when the ratio was close to unity. Individual body weights and the annual course of weight class distribution showed no distinct peculiarities, although body weight increased relatively slowly in late winter. Low juvenile survival, relatively low litter sizes and early termination of breeding were special features of the population. Furthermore, very few juveniles matured in the year of birth, and the best winter survival was found in mice born in the middle of the breeding season. Activity ranges were small compared with those given in the literature, and space use was similar in both sexes. As a direct effect of the habitat conditions, the diet was largely dominated by weed seeds. The possible reasons for and causal relations of these features are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317312
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Circadian activity patterns, photoperiodic responses and population cycles in voles (1987)
    Springer
    Oecologia 71 (1987), S. 573-576 
    Details
    ISSN: 1432-1939
    Keywords: Microtines ; Population cycle ; Photoperiodism ; Reproduction ; Circadian system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379300
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Avian predation upon a mixed community of common voles (Microtus arvalis) and wood mice (Apodemus sylvaticus) (1988)
    Springer
    Oecologia 75 (1988), S. 451-455 
    Details
    ISSN: 1432-1939
    Keywords: Pellet analysis ; Selective avian predation ; Small rodent populations ; Social rank ; Varying vulnerability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pellets of diurnal avian predators (mainly kestrels and buzzards) were analysed to prove the hypothesis of selective predation for a mixed population of small rodents. It was found that voles heavily predominated as prey over mice (up to a factor of 19 during winter). Within both prey species, predation focussed on distinct parts of the populations: during winter the heaviest specimens were preferentially captured, during summer the subadults were in an exposed position. In the voles, an additional predominance of males occurred (up to a factor of 5.2 during summer). These findings verify the assumption of Errington (1956) that speciments of a low social rank are susceptible to the highest risk of predation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376950
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Circadian activity patterns, photoperiodic responses and population cycles in voles (1987)
    Springer
    Oecologia 71 (1987), S. 568-572 
    Details
    ISSN: 1432-1939
    Keywords: Microtines ; Circadian activity behaviour ; Long-term variations ; Population cycles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Patterns of above-ground activity were recorded in two free-ranging populations of Microtus agrestis (L.) and one population of M. arvalis (Pall.) over several years by means of passage counters. Long-term variations of the circadian patterns were observed, but did not repeat themselves in a 12-month cycle. Variations in all three populations could be described by a sinusoidal function of an 18-month period. Maxima and minima of the sine-function were connected to distinct photoperiods (equinoxes and solstices). In a cyclic North Swedish population, the sine-function was superimposed by a second function which shows saturation behaviour. The relevance of these findings is discussed with respect to vole population cycles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379299
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    A spontaneous temperature sensitive mutant of Japanese encephalitis virus: Preliminary characterization (1977)
    Springer
    Archives of virology 54 (1977), S. 165-176 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A spontaneously arising temperature sensitive (ts) mutant of Japanese encephalitis virus (JEV),ts 104, was isolated from chick fibroblast (CF) cell cultures of JEV strain M1/311. Straints 104 was plaque purified and characterized to ascertain its potential as a candidate for a live vaccine. Parameters of its growth, temperature lability, immunogenicity and virulence were examined.Ts 104 has been shown to be a stablets JEV strain, multiplying as well as the parent strain in CF cultures at 35° C, but not multiplying at 39° C. It was avirulent for embryonated chicken eggs incubated at 39° C and of reduced virulence for intracerebrally (i. c.) inoculated mice as measured by LD50 in weanling mice and average day of death in weanling and suckling mice. Intraperitoneal injection of adult mice with either parent orts strain resulted in similar levels of protection against challenge with either strain. The potential ofts 104 as a candidate live JEV vaccine strain is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01314783
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...