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The UV irradiation of formamide (HCONH(sub 2)) in xenon, nitrogen, argon and neon cryogenic matrices is monitored by Fourier transform infrared (FT-IR) spectroscopy. The results relative to photolysis of formimidic acid performed with broad-band UV irradiation of a H(sub 2) lamp irradiating at lamda > 160 gives evidence of dehydrogenation and dehydration processes that lead to formation of complexes such as HNCO.H(sub 2) and HCN.H(sub 2)O.

FTIR spectroscopy is used to show that carbodiimide can be formed from cyanamide at low temperature (10K), by a photochemical process in argon matrix, in water matrix, or in solid film. A report on experimental evidence about the carbodiimide formation when cyanamide is condensed at low temperature (50-140K) on an amorphous water ice surface, or when it is trapped in water ice bulk, is presented.

The cyanoacetylene adsorption and desorption on amorphous ice film are monitored by FT-IR matrix isolation spectroscopy using the temperature-programmed desorption method. The calculations confirm the electrostatic nature of the interaction forces, and it was seen that HC3N acts as both an electrophilic and a nucleophilic molecules.

Research was conducted to examine the structure and energy properties of the H2O/C3O2 (D2O/C3O2) and NH3/C3O2 (15NH3/C3O2) 1:1 complexes using ab initio calculations and FT-infrared spectroscopy. A large shift of the nu-CCO stretching modes to lower frequencies have characterized the complexes trapped in solid argon matrices. Results indicate a pre-reactive intermediate of an 1,4 nucleophilic addition.

We use Very High Resolution Mass Spectrometry for analyses of the soluble fraction of yellow stuff produced in laboratory. Their analyses show that they are composed of molecules with high molecular weight (m/z>4000). Fragmentations suggest that grafted molecules constitute a part of them. Hexamethylenetetramine derivatives have also been detected. First results and further analytical developments will be presented to facilitate the understanding of the residue composition and of its chemical evolution. Furthermore, we present for the first time the concept of the VAHIIA project which concerns the analysis of volatiles coming from the heating of interstellar ice analogues.

Mass spectrometry and Fourier transform infrared (FTIR) spectroscopy are used for studying low temperature reactivity of methylamine (C[H.sub.3]N[H.sub.2]) and carbon dioxide (C[O.sub.2]) mixed within different ratios. The studies have shown that amine have reacted at low temperature in interstellar ices rich in C[O.sub.2] that are a privilaged place of complex molecules formation, before being later released into 'hot core' regions.

Vacuum ultraviolet (VUV) irradiation at wavelengths of gamma > 160 nm of urea-h4 (NH2CONH2) and urea-d4 (ND2COND2) is monitored by Fourier transform infrared spectroscopy in argon and xenon matrixes. The results reveal that vacuum ultraviolet (VUV) irradiation of urea-h4 and urea-d4 isotopomer in argon at 10K leads to the formation of molecular complexes HNCO:NH3, Co: N2H4 and their deuterated analogues.

The reactivity of HNCO with molecular NH3 and with NH3 ices is investigated between 10 and 150 K with use of FT-IR spectroscopy and ab initio calculations. When HNCO is co-deposited with NH3 in argon matrix at 10 K a predominant 1:1 hydrogen-bonded complex is formed in which HNCO displays a proton donor character.

Soluble and insoluble organic matter (IOM) is a key feature of primitive carbonaceous chondrites. We observe the formation of organic materials in the photothermochemical treatment of astrophysical ices in the laboratory. Starting from a low vacuum ultraviolet (VUV) irradiation dose on templates of astrophysical ices at 77 K, we obtain first a totally soluble form of organic matter at room temperature. Once this organic residue is formed, irradiating it further in vacuum results in the production of a thin altered dark crust on top of the initial soluble one. The whole residue is studied here by non-destructive methods inducing no alteration of samples, visible microscopy and mid-infrared (micro-)spectroscopy. After water extraction of the soluble part, an insoluble fraction remains on the sample holder which provides a largely different infrared spectrum when compared to the one of the soluble sample. Therefore, from the same VUV and thermal processing of initial simple ices, we produce first a soluble material from which a much larger irradiation dose leads to an insoluble one. Interestingly, this insoluble fraction shows some spectral similarities with natural samples of IOM extracted from two meteorites (Tagish Lake and Murchison), selected as examples of primitive materials. It suggests that the organic molecular diversity observed in meteorites may partly originate from the photo and thermal processing of interstellar/circum-stellar ices at the final stages of molecular cloud evolution towards the build-up of our Solar system. [ABSTRACT FROM AUTHOR]

Next to water, methanol is one of the most abundant molecules in astrophysical ices. A new experimental approach is presented here for the direct monitoring via gas chromatography coupled to mass spectrometry GC-MS of a sublimating photo-processed pure methanol ice. Unprecedentedly, in a same analysis, compelling evidences for the formation of 33 volatile organic compounds are provided. These latter are C1 to C6 products including alcohols, aldehydes, ketones, esters, ethers and carboxylic acids. Few C3 and all C4 detected compounds have been identified for the first time. Tentative detection of few C5 and C6 compounds are also presented. GC-MS allows for the first time the direct quantification of C2 to C4 photoproducts and shows that their abundances decrease with the increase of their carbon chain length. These qualitative and quantitative measurements provide important complementary results to previous experiments, and present interesting similarities with observations of sources rich in methanol. [ABSTRACT FROM AUTHOR]