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IR spectra of pure solid nitrogen at 20 K after photolysis at wavelengths 130 nm (curve A), 121.6 nm (curve B), and 91.6 nm (curve C) for 15 minutes. A resolution of 0.5 cm −1 was used in the measurements.
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Vacuum-ultraviolet light from a synchrotron was applied to record absorption spectra in the region of 105-170 nm with a resolution of 0.2 nm and for the photolysis of pure solid N2 and CH4 dispersed in solid N2 (CH4/N2 = 1/100 for absorption and 1/500 for photolysis) at 20 K. After photolysis of the icy samples at wavelengths 130 nm (9.5 eV), 121.6...
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Context 1
... IR absorption spectrum of pure solid N 2 at 20 K mainly exhibits a weak feature at 2327.8 cm −1 with an FWHM of 1.7 cm −1 absorption. After irradiation with VUV photons, strong absorption features appear at 1657.8 and 1652.6 cm −1 with FWHM 0.6 cm −1 (Figure 3, curves A-C). These features are assigned to the known ν 3 mode of azide, N 3 ( Tian et al. 1988). ...
Citations
... Nitrogen solids gained general recognition as classical model molecular crystals which attract much attention in diverse fields of science: physics and chemistry of interstellar and solar systems, [1][2][3][4][5][6][7][8] material science, specifically, the problem of polynitrogen compounds considered as environment-friendly high energy-density materials (HEDM). [9][10][11][12] Energy storage, transformation, and its release are the focus of studies, and among the methods used spectroscopy is one of the most effective. ...
New results on the study of radiation effects in solid nitrogen and N2-doped Ne matrix are presented, with a focus on the so-called γ-line origin. The irradiation was carried out in dc regime with an electron beam of subthreshold energy. The relaxation dynamics was monitored by emission spectroscopy: cathodoluminescence (CL) and nonstationary luminescence (NsL), along with current activation spectroscopy. Thermally stimulated luminescence (TSL) and exoelectron emission (TSEE) of pure nitrogen and N2 in the Ne matrix were measured in a correlated manner. Three emission bands were recorded in the NIR CL spectra of solid N2: 794, 802, and 810 nm. The band at 810 nm was detected for the first time. These three bands are characterized by similar behavior and form molecular series with spacing between adjacent vibrational energy levels of the ground state of 125 and 123 cm−1. These data cast doubt on the recently made assumption that the γ-line is attributed to the emission of the nitrogen anion N− [R. E. Boltnev, I. B. Bykhalo, I. N. Krushinskaya et al. Phys. Chem. Chem. Phys. 18, 16013 (2016)]. The processes of electron attachment and neutralization of positively charged species are discussed. It has been established that the γ-line in the TSL spectra of pure nitrogen and N2-doped Ne matrix correlates with TSEE currents and recombination emission of O+, N2+, and N4+ ions, which indicates its connection with the neutralization reaction. The measurement of NsL supported this conclusion. A new possible assignment of the γ-line and its satellites to the emission of tetranitrogen N4 is discussed.
... Numerous efforts have been made to simulate radiation-induced processes in the laboratory using a variety of techniques surveyed in Ref. [9]. Various types of ionizing radiation were used to study the radiation behavior of methane and methane-rich ices-ions [10][11][12][13][14][15][16][17][18][19], electrons [20][21][22][23][24][25][26][27][28][29] and photons [26,[30][31][32][33][34][35]. ...
The relaxation processes induced by exposure of the Ar matrices doped with CH4 (0.1–10%) to an electron beam were studied with a focus on the dynamics of radiolysis products—H atoms, H2 molecules, CH radicals, and energy transfer processes. Three channels of energy transfer to dopant and radiolysis products were discussed, including free charge carriers, free excitons and photons from the “intrinsic source” provided by the emission of the self-trapped excitons. Radiolysis products along with the total yield of desorbing particles were monitored in a correlated manner. Analysis of methane transformation reactions induced by free excitons showed that the CH radical can be considered a marker of the CH3 species. The competition between exciton self-trapping and energy transfer to the dopant and radiolysis products has been demonstrated. A nonlinear concentration behavior of the H atoms in doped Ar matrices has been established. Real-time correlated monitoring of optical emissions (H atom and CH3 radicals), particle ejection, and temperature revealed a nonmonotonic behavior of optical yields with a strong luminescence flash after almost an hour of exposure, which correlated with the explosive pulse of particle ejection and temperature. The connection of this phenomenon with the processes of energy transfer and recombination reactions has been established. It is shown that the delayed explosive ejection of particles is driven by both the recombination of H atoms and CH3 radicals. This occurs after their accumulation to a critical concentration in matrices at a CH4 content C ≥ 1%.
... Numerous efforts have been made to simulate radiation-induced processes in the laboratory using a variety of techniques surveyed in Rev. [9]. Various types of ionizing radiation were used to study radiation behavior of methane and methane-rich ices -ions [10][11][12][13][14][15][16][17][18][19], electrons [20][21][22][23][24][25][26][27][28][29] and photons [26,[30][31][32][33][34][35]. ...
The relaxation processes induced by an exposure of the Ar matrices doped with CH4 (0.1 – 10%) to an electron beam were studied with a focus on the dynamics of radiolysis products – H atoms, H2 molecules, CH radicals, and energy transfer processes. Three channels of energy transfer to dopant and radiolysis products were discussed: by free charge carriers, free excitons and photons from the “intrinsic source” provided by emission of the self-trapped excitons. Radiolysis products along with the total yield of desorbing particles were monitored in a correlated manner. Analysis of methane transformation reactions induced by free excitons showed that the CH radical can be considered as a marker of the CH3 species. The competition between exciton self-trapping and energy transfer to the dopant and radiolysis products has been demonstrated. A nonlinear concentration behavior of the H atoms in doped Ar matrices has been established. Real-time correlated monitoring of optical emissions (H atom and CH3 radicals), particle ejection, and temperature revealed a nonmonotonic behavior of optical yields with a strong luminescence flash after almost an hour of exposure, which correlated with explosive pulse of particle ejection and temperature. The connection of this phenomenon with the processes of energy transfer and radical-radical recombination is discussed.
... There are a handful of existing laboratory studies focused on elucidating possible ice formation pathways of nitriles. Wu et al. (2012) produced HCN (and HNC) through UV irradiation of simple hydrocarbons embedded in a 20 K N 2 matrix. A similar experiment was carried out by Wu et al. (2013), who used electron bombardment to irradiate CH 4 diluted in a 10 K N 2 ice matrix and also found efficient HCN (and HNC) formation. ...
Nitriles are key reactants in prebiotic synthesis networks of RNA bases and amino acids. The detection of CH 3 CN and other complex nitriles in planet-forming disks suggests that such molecules are regularly delivered to nascent planets, increasing the likelihood of origins of life outside of Earth. In this paper, we investigate the formation of CH 3 CN and the closely related imines from the vacuum ultraviolet irradiation of NH 3 :C 2 H 6 , NH 3 :C 2 H 4 , and NH 3 :C 2 H 2 ice mixtures at 10–50 K. CH 3 CN is formed in a subset of these experiments, with the highest yield of ∼5% with respect to the initial NH 3 abundance achieved at the lowest ice temperatures for the least saturated hydrocarbon ice mixture. We find that the imine CH 3 CH=NH serves as an intermediate for the production of CH 3 CN in all ices and its yield generally appears higher than that of CH 3 CN. If the investigated ice chemistry is an important formation pathway of nitriles, we should observe CH 3 CH=NH > CH 3 CN. The opposite is true toward the Galactic Center, while no published constraints on CH 3 CH=NH exist in disks. Such constraints are needed to distinguish between the formation pathway presented in this work and other possible gas and ice nitrile formation pathways in different astrophysical environments. In the meantime, we conclude that NH 3 :hydrocarbon ice photochemistry is an excellent candidate for efficient low-temperature interstellar imine production.
... The first reason is that nitrogen molecules do not absorb VUV light of 150 nm and longer wavelengths 34) , and quartz glass does not transmit VUV light of 150 nm and shorter wavelengths 35) . ...
This study, reports on ozone catalytic oxidation of dimethyl sulfide; a major odor material of waste water facilities. Xenon excimer lamp (XEL) was used for ozone generation, and iodine compounds (I- and IO3-) were utilized as a catalyst. Three types of activated carbon, activated carbon impregnated with iodine compounds and sulfate (AC-I/S), activated carbon impregnated with iodine (AC-I) and activated carbon without impregnation (AC) were tested as catalysts. Only AC-I/S had catalytic activity in the dynamic adsorption experiment. Breakthrough time of dimethyl sulfide was increased by 10 times by adding ozone in AC-I/S. Catalyst characterization by pH measurement and XPS analysis suggested that catalytic activity of iodine compounds was influenced by the surface acidity. These results suggest that the XEL and AC-I/S are applicable in ozone catalytic oxidation in gas treatments.
... Photoabsorption and PL experiments were performed at beamline TLS-03 of the National Synchrotron Radiation Research Center (NSRRC) in Taiwan; the experimental setup is described elsewhere (Chou et al. 2020. Exposure of graphene samples to intense far-UV light in vacuum was performed at undulator beamline TLS-21A2, NSRRC (Wu et al. 2012;Lin et al. 2022). Conditions of exposure to far-UV light under large and small densities of photon flux were achieved via an adjustment of the position of a sample relative to the focal point of the beam. ...
Extended red emission (ERE) is a broad feature in the spectral region of 500–900 nm commonly observed in a wide range of circumstellar and interstellar environments. Although the observational constraints for ERE are well established, definitive identifications of the carriers and associated processes complying with these constraints remain unanswered. We report a plausible two-step model involving far-ultraviolet (UV)-irradiated single-layer graphene (SLG), considered as large polycyclic aromatic hydrocarbons, to meet these constraints and supported by laboratory experiments. The far-UV-treated SLG, producing structural defects and graphene quantum dots, showed photoluminescence excitation spectrum extending from the far-UV to UV–visible region, hence meeting the requirements of far-UV light and high photon conversion efficiency. Furthermore, a photoluminescence band shifted from ∼585 to ∼750 nm for high-dose-exposed SLG agrees with the observed redshift of the ERE band in regions under a greater far-UV radiation density.
... The band positions are determined in this study. The notation (p) indicates the most prominent absorption features shown in Figures 2 and 3. absorption of UV light by N 2 (Hudson & Moore 2002;Kobayashi et al. 2008;Wu et al. 2012;Islam et al. 2014). ...
The origin of organic compounds detected in meteorites and comets, some of which could have served as precursors of life on Earth, remains an open question. The aim of the present study is to make one more step in revealing the nature and composition of organic materials of extraterrestrial particles by comparing infrared spectra of laboratory-made refractory organic residues to spectra of cometary particles returned by the Stardust mission, interplanetary dust particles, and meteorites. Our results reinforce the idea of a pathway for the formation of refractory organics through energetic and thermal processing of molecular ices in the solar nebula. There is also the possibility that some of the organic material had formed already in the parental molecular cloud before it entered the solar nebula. The majority of the IR “organic” bands of the studied extraterrestrial particles can be reproduced in the spectra of the laboratory organic residues. We confirm the detection of water, nitriles, hydrocarbons, and carbonates in extraterrestrial particles and link it to the formation location of the particles in the outer regions of the solar nebula. To clarify the genesis of the species, high-sensitivity observations in combination with laboratory measurements like those presented in this paper are needed. Thus, this study presents one more piece of the puzzle of the origin of water and organic compounds on Earth and motivation for future collaborative laboratory and observational projects.
... The first continuum peak and second continuum peak are about same order of value when the gas pressure is about 5-20 kPa [47], although the first continuum of the xenon excimer peak at 152 nm was not detected. This could be due to the VUV adsorption by quartz glass [48] or nitrogen molecules [49]. Figure 6 shows the emission spectra of the excimer lamp when N 2 gas was flowed to the SUS chamber and the duty ratio of the ON/OFF signal was 100%. ...
... The first continuum peak and second continuum peak are about same order of value when the gas pressure is about 5-20 kPa [47], although the first continuum of the xenon excimer peak at 152 nm was not detected. This could be due to the VUV adsorption by quartz glass [48] or nitrogen molecules [49]. VUV light emission is generated by the following process in Equations (3)-(5) [50]. ...
... The mechanism of the excimer lamp that does not generate NOx is described as below. The first reason is that nitrogen molecules do not absorb VUV light of 150 nm and longer wavelengths [48], and quartz glass does not transmit VUV light of 150 nm and shorter wavelengths [49]. The second reason is that if NOx was generated slightly, NOx could be converted to nitrogen molecules by photochemical reactions in accordance with Equations (13)-(16) [57]. ...
Gaseous sulfur compounds are emitted from many facilities, such as wastewater facilities or biomass power plants, due to the decay of organic compounds. Gaseous dimethyl sulfide removal by ozone catalytic oxidation was investigated in this study. A Vacuum-Ultra-Violet (VUV) xenon excimer lamp of 172 nm was used for ozone generation without NOx generation, and activated carbon impregnated with iodic acid and H2SO4 was utilized as a catalyst. Performance assessment of dimethyl sulfide removal ability was carried out by a dynamic adsorption experiment. Empty-Bed-Contact-Time (EBCT), superficial velocity, concentration of dimethyl sulfide, temperature and humidity were set at 0.48 s, 0.15 m/s, 3.0 ppm, 25 °C and 45%, respectively. Without ozone addition, the adsorption capacity of impregnated activated carbon was 0.01 kg/kg. When ozone of 7.5 ppm was added, the adsorption capacity of impregnated activated carbon was increased to 0.15 kg/kg. Methane sulfonic acid, a reaction product of dimethyl sulfide and ozone, was detected from the activated carbon. The results suggest that the VUV and activated carbon impregnated with iodic acid and H2SO4 are workable for ozone catalytic oxidation for gas treatments.
... The practical range r of 1 keV electrons in Ar lattice (r = 20 nm [50]) exceeds the cluster's diameter δ = 4.4 nm (at N = 1.2⋅10 3 atom/cluster), while in solid films the practical range r of 1.5 keV incident electrons r ~ 100 nm is much less than the films thickness d = 25 μm. This results in an electron trapping and the accumulation of excess negative charge in the Ar matrix [54]. It has been shown [30] that because of the small penetration depth of electrons the bulk of the matrix is excited preferentially by free excitons and photons with an energy of 9.76 eV, the most intense emission band of the matrix (excitons self-trapped into the configuration of * 2 Ar ) and only thin subsurface layer ~ 100 nm is excited by electrons. ...
... The first step in the formation of an excited H * atom via scenario (iii) is the dissociation of a neutral CH 4 molecule. As it was mentioned the band Ar 2 * falls into CH 4 absorption band, while the band (Ar 4 + ) * is near the onset of absorption [54]. The formation of excited H * atoms in the "exciton-induced" scenario (iv) is based on the excitation of the ground state H atoms, formed via fragmentation of CH 4 [Eqs. ...
... However, addition of CH 4 molecules completely quenched this band. In view of the low absorbance of CH 4 near 9 eV [54] this fact points to the participation of Ar holes in H * atoms desorption in clusters. Quenching of both components of Ar emissionneutral * 2 Ar and charged one (Ar 4 + ) * , points to the involvement of both scenarios of H * atoms desorption in clusters: via excitons and holes. ...
Desorption of excited hydrogen atoms was detected from both solid Ar doped with CH4 and free nanoclusters Ar/CH4 at irradiation with an electron beam. It was monitored by an emission of the Lyman-a line. Measurements of cathodoluminescence (CL) spectra in the VUV range were performed within the CH4 concentration limits 0.1–10% in the solid matrix. The CL of free clusters with an average size of 1200 atoms per cluster was detected from pure Ar cluster jet and from Ar clusters doped with 0.1% CH4. The mechanisms of desorption of electronically excited H* atoms from solids and clusters are proposed on the basis of an analysis of energy transfer pathways with the final stage of relaxation — population of the n = 3 state of hydrogen atoms.
... It should be stressed out that neither acetonitrile nor isoacetonitrile was detected in the VUV and electron irradiated C 2 H 2 :N 2 and C 2 H 4 :N 2 mixed ices. 34,35 Extensive studies were performed with the mixed CH 4 :N 2 ices (see ref. [36][37][38][39][40][41] and references therein). However, to the best of our knowledge, there is only one recent report on CH 3 CN formation in the ion-irradiated methane-nitrogen ices at 9 K 41 and the reaction of CH 2 with HCN was suggested to be responsible for CH 3 CN production under such experimental conditions. ...
Nitriles are important constituents of extraterrestrial media. Nitriles are supposed to play a crucial role in prebiotic chemistry occurring in the interstellar medium. In this work, we have investigated the low-temperature radiation-induced transformations of a 1 : 1 CH4HCN complex as a plausible precursor of the simplest nitriles using the matrix isolation approach with FTIR spectroscopic detection. The parent complexes isolated in a noble gas (Ng) matrix were obtained by deposition of the CH4/HCN/Ng gaseous mixture and characterized by comparison of experimental complexation-induced shifts of the HCN fundamentals with the results of the ab initio calculations. It was found that the X-ray irradiation of low-temperature matrices containing the isolated 1 : 1 CH4HCN complex resulted in the formation of acetonitrile (CH3CN) and isoacetonitrile (CH3NC) and it appears to be the first experimental evidence for the formation of C2 nitriles (acetonitrile and isoacetonitrile) from such a "building block". Additionally, a 1 : 1 CH4HNC complex was tentatively assigned to the irradiated Ar and Kr matrices. It is demonstrated that the matrix has a strong effect on the CH3CN/CH3NC yield ratio, which dramatically increases in the row Ar < Kr < Xe. Also, the efficiency of the radiation-induced formation of the CH4HNC complex was shown to decrease from Ar to Kr. It is believed that the proposed pathway for acetonitrile formation may be a significant step in the radiation-induced evolution leading to complex organic molecules and biomolecules under astrochemical conditions. Furthermore, the obtained results provide a prominent example of the impact of very weak intermolecular interactions on the radiation-induced transformations in cold media.
