In the environments where stars and planets form, about one percent of mass is in form micro-meter sized particles known as dust. However small insignificant these dust grains may seem, they are responsible for production simplest (H2) to most complex (amino-acids) molecules observed our Universe. Dust recognized powerful nano-factories that produce chemical species. However, mechanism converts species on gas remains elusive. Here we report experimental evidence forming interstellar analogs...

Carbon monoxide is after H2 the most abundant molecule identified in interstellar medium (ISM), and used as a major tracer for gas phase physical conditions. Accreted at surface of water-rich icy grains, CO considered to be starting point complex organic – presumably prebiotic chemistry. Non-thermal desorption processes, especially photodesorption by UV photons, are seen main cause that drives gas-to-ice balance colder parts ISM. The process known efficient wavelength-dependent, but,...

The amount of methanol in the gas phase and CO depletion from are still open problems astrophysics. In this work, we investigate solid-state hydrogenation CO-bearing species via H-exposure carbon monoxide, formaldehyde, methanol-thin films deposited on cold surfaces, paying attention to possibility a return phase. products probed infrared spectroscopy (reflection absorption spectroscopy), two types mass protocols: temperature-programmed desorption, during-exposure desorption techniques. case...

Any evolving system can change state via thermal mechanisms (hopping a barrier) or quantum tunneling. Most of the time, efficient classical dominate at high temperatures. This is why an increase temperature initiate chemistry. We present here experimental investigation O-atom diffusion and reactivity on water ice. explore 6-25 K range submonolayer surface coverages. derive law observe transition from to diffusion. Despite mass O, tunneling even 6 K. As consequence, solid-state astrochemistry...

In this article, we report on a Fourier transform infrared study of absorption bands belonging to small-sized water clusters formed in continuous slit nozzle expansion vapor seeded argon carrier gas. Clear signatures free and H-bonded OH vibrations aggregates from dimer pentamer are seen our spectra. Following an increase backing pressure, the position cluster varies those characteristics isolated gas phase known for trapped static matrix. These variations can be interpreted terms sequential...

A series of hydrogen bonded complexes involving oxirane and water molecules have been studied. In this paper we report on the vibrational study oxirane−water complex (CH2)2O−H2O. Neon matrix experiments ab initio anharmonic calculations performed, providing a consistent set frequencies coupling constants. The implementation new large flow supersonic jet coupled to Bruker IFS 125 HR spectrometer at infrared AILES beamline French synchrotron SOLEIL (Jet-AILES) enabled us record first...

A high temperature source has been developed and coupled to a resolution Fourier transform spectrometer record emission spectra of acetylene around 3 μm up 1455 K under Doppler limited (0.015 cm−1). The ν3-ground state (GS) ν2+ν4+ν5 (Σu+ Δu)-GS bands 76 related hot bands, counting e f parities separately, are assigned using semiautomatic methods based on global model reproduce all vibration-rotation states. Significantly higher J-values than previously reported observed for 40 known...

At the low temperatures of interstellar dust grains, it is well established that surface chemistry proceeds via diffusive mechanisms H atoms weakly bound (physisorbed) to surface. Until recently, however, was unknown whether heavier than hydrogen could diffuse rapidly enough on grains react with other accreted species. In addition, models still require simple reduction as oxidation reactions occur explain abundances various molecules. this paper we investigate O-atom diffusion and reactivity...

We report the results of an experimental study related to relaxation nuclear spin isomers water molecule in a supersonic expansion. Rovibrational lines both ortho and para were recorded spectral range H2O stretching vibrations at around 3700 cm–1 using FTIR direct absorption. Water vapor seeded argon, helium, or oxygen mixture argon was expanded into vacuum through slit nozzle. The partial pressure varied over wide from 1.5 102.7 hPa, corresponding molar fraction varying between 0.2 6.5%....

In this paper, we report a combined theoretical and experimental study of coronene:water interactions in low temperature argon matrices. The calculations were performed using the mixed density functional-based tight binding/force field approach. results are discussed light matrix isolation FTIR spectroscopic data. We show that, solid phase, (C24H12)(H2O)n (n ≤ 6) σ-type complexes, i.e. with water molecules coordinated on edge coronene, formed, whereas gas π-interaction is preferred. These...

Cassini-Huygens data are used to reexamine the potential sources of D/H enhancement over solar, measured in methane, Titan's atmosphere. Assuming that system is closed with respect carbon, use constraints from Huygens probe for determination current mass atmospheric methane and most up-to-date Cassini CIRS infrared spectra allow us show photochemical enrichment deuterium not sufficient be sole mechanism yielding value. A possible fractionation between CH3D CH4 during escape process may...

The photochemistry of ices with polycyclic aromatic hydrocarbons (PAHs) has been extensively studied, but to date no investigation made PAHs in interaction low numbers (n < 4) molecules water. We performed photochemical matrix isolation studies coronene:water complexes, probing the argon FTIR spectroscopy. find that coronene readily reacts water upon irradiation a mercury vapour lamp produce oxygenated PAH photoproducts, and we postulate reaction mechanism via charge transfer Rydberg state....

Numerous hydrogenated molecules observed in comets and the interstellar medium present nuclear spin isomers. The non-thermal ortho: para ratios measured space are believed to be of high diagnostic value, allowing remote measurement physical conditions prevailing past, such as initial temperature associated with a molecular formation or condensation. lack laboratory studies on interactions at gas-solid interface limits our current interpretation observations. Recent progress conversion (NSC)...

Hot temperature minerals have been detected in a large number of comets and were also identified the samples Comet Wild 2 that returned by Stardust mission. Meanwhile, observations distribution hot young stellar systems suggest these materials produced inner part primordial nebula transported outward formation zone comets. We investigate possibility photophoresis provides viable mechanism to transport high-temperature from solar system regions which forming. use grid time-dependent disk...

New molecular beam scattering experiments are reported for the water–hydrogen system. Integral cross sections of first rotational excitations para- and ortho-H2O by inelastic collisions with normal-H2 were determined crossing a H2O seeded in He H2. H2 cooled supersonic expansion down to their lowest levels. Crossed-beam performed at collision energies from 15 cm–1 (below threshold excitation excited state H2O: 18.6 cm–1) up 105 varying angle. The measured state-to-state cross-sections...

The rate of the gas-phase N((4)S) + C2N(X(2)Πi) reaction has been measured in a continuous supersonic flow reactor down to 54 K through relative-rate method using OH(X(2)Π) → H((2)S) NO(X(2)Π) as reference. microwave discharge technique was employed produce high concentrations atomic nitrogen. Pulsed laser photolysis precursor molecules Cl3C2N and H2O2 at 212 nm situ led C2N OH radical formation, respectively. constant is shown be approximately independent temperature, contrast previous...

Recently [arXiv:astro-ph/0612155] we presented a formal mathematical proof that, contrary to widespread misconception, cosmological expansion cannot be understood as the motion of galaxies in non-expanding space. We showed that redshift must physically interpreted Although our was generally accepted, few authors disagreed. rebut their criticism this Note.