Methods by which experimental measurements of thermal desorption can be applied in astrophysical environments have been developed, using the sublimation of solid methanol as an example. The temperature programmed desorption of methanol from graphitic, amorphous silica and polycrystalline gold substrates was compared, with the kinetic parameters of desorption extracted by either a leading edge a...

The desorption of molecular species from ice mantles back into the gas phase in molecular clouds results from a variety of very poorly understood processes. We have investigated three mechanisms; desorption resulting from H2 formation on grains, direct cosmic ray heating and cosmic ray induced photodesorption. Whilst qualitative differences exist between these processes (essentially deriving fr...

H.-R. Schulten and W. D. Lehmann Institute of Physical Chemistry, University of Bonn, Wegeierstraße 12, D-5300 Bonn Z. Naturforsch. 83 b, 770-781 (1978); received March 21, 1978 Field Desorption Mass Spectrometry, a-Amino Acid Methionine The fragmentation of methionine in field desorption mass spectrometry has been studied. Decomposition mechanisms are described which are based on stable isotop...

in this study, the batch equilibrium method was used to conduct metribuzin adsorption/desorption experiments with eight soils from different regions of iran. the results indicated that the organic carbon (oc) content, clay content, cation exchange capacity (cec), and ph had a combined effect on the metribuzin adsorption on soil. under the experimental conditions, the adsorption amount of metrib...

Commonly used soil water retention, θ(h), and moisture capacity, C(h), functions implicitly assume that: i) the θ(h) data curve is sigmoid-shaped with an inflection; ii) C(h) has a value of zero at saturation. Desorption measurements on intact soils indicate, however, that frequently convex-monotonic in shape no inflection, saturation often finite negative rather than zero. As these model-data ...

3-Hydroxypropionaldehyde (3HPA), a potential C3-platform chemical for a biobased industry, is produced from glycerol using Lactobacillus reuteri through its glycerol dehydratase activity. However, the process is characterized by low yield and productivity due to toxic effects of 3HPA on the biocatalyst activity. In this study, a semicarbazide-functionalized resin was prepared, evaluated for ads...

abstract herbicides are the main sources of soil and water pollution in paddy fields. herbicides mobility to the surface and ground water is a major concern for human health and the environment. it is, therefore, necessary to investigate their fate and their interactions in natural ecosystems. to meet this purpose, field experiments were conducted to measure kinetic of thiobencarb dissipation i...

The dynamics of oligomer desorption from surfaces have been studied by measuring the desorption kinetics of a set of n-alkanes from the surface of single crystalline graphite. Desorption rates were measured using a set of 21 monodispersed n-alkanes (CNH2N12,5<N<60) each adsorbed at coverages in the range ,0.1 to .1 monolayers. Desorption is observed to be a first-order process with a desorption...

The dissociative adsorption energy of oxygen on Pt(111) is known to be coverage dependent. Simple Redhead analysis of temperature programmed desorption (TPD) experiments that assumes a coverage independent desorption barrier can lead to errors in estimated properties such as desorption barriers and adsorption energies. A simple correction is to assume a linear coverage dependence of the desorpt...

T h e r m a l desorption spectroscopy (TDS) based on the mass spectroscopy of thermal ly evolved hydrogen is used for desorption analysis of amorphous hydrogenated silicon (a-Si:H). Two series of glow discharge chemical vapour deposited a-Si:H were investigated by the T D S method . Cons tan t t e m p e r a t u r e growth ra te enabled to determine t empera tu re regions of hydrogen evolution a...