Abstract:Large-scale plasma was created in molecular gases (CO, CO2, N2, H2O) and their mixtures by high-power laser-induced dielectric breakdown (LIDB). Compositions of the mixtures used are those suggested for the early earth's atmosphere of neutral and/or mildly reducing character. Time-integrated optical spectra emitted from the laser spark have been measured and analyzed. The spectra of the plasma generated in the CO-containing mixtures are dominated by emission of both C2 and CN radicals. A vibrational temperatur… Show more
“…The same behavior was observed starting with HCONH 2 as a single molecular source of C, H, O & N. Figure 1 shows typical emission spectra of laser induced breakdown shock wave plasma in such simple atmospheres of C, H, O & N bearing molecules. Typical vibrational temperatures of molecular species range 12,33–35 between 4200–6500 K while excitation temperature of atoms does not exceed 9300 K 33 . This figure is compiled from several measurements published in our previous papers so as to show typical, representative spectra 12,33,34,36 .Figure 1Compiled emission spectrum of laser induced breakdown in mixture of C, H, O & N bearing molecules 12,33,34,58 .…”
Section: Resultsmentioning
confidence: 99%
“…Compiled emission spectrum of laser induced breakdown in mixture of C, H, O & N bearing molecules 12,33,34,58 .…”
Recent results in prebiotic chemistry implicate hydrogen cyanide (HCN) as the source of carbon and nitrogen for the synthesis of nucleotide, amino acid and lipid building blocks. HCN can be produced during impact events by reprocessing of carbonaceous and nitrogenous materials from both the impactor and the atmosphere; it can also be produced from these materials by electrical discharge. Here we investigate the effect of high energy events on a range of starting mixtures representative of various atmosphere-impactor volatile combinations. Using continuously scanning time–resolved spectrometry, we have detected ·CN radical and excited CO as the initially most abundant products. Cyano radicals and excited carbon monoxide molecules in particular are reactive, energy-rich species, but are resilient owing to favourable Franck–Condon factors. The subsequent reactions of these first formed excited species lead to the production of ground-state prebiotic building blocks, principally HCN.
“…The same behavior was observed starting with HCONH 2 as a single molecular source of C, H, O & N. Figure 1 shows typical emission spectra of laser induced breakdown shock wave plasma in such simple atmospheres of C, H, O & N bearing molecules. Typical vibrational temperatures of molecular species range 12,33–35 between 4200–6500 K while excitation temperature of atoms does not exceed 9300 K 33 . This figure is compiled from several measurements published in our previous papers so as to show typical, representative spectra 12,33,34,36 .Figure 1Compiled emission spectrum of laser induced breakdown in mixture of C, H, O & N bearing molecules 12,33,34,58 .…”
Section: Resultsmentioning
confidence: 99%
“…Compiled emission spectrum of laser induced breakdown in mixture of C, H, O & N bearing molecules 12,33,34,58 .…”
Recent results in prebiotic chemistry implicate hydrogen cyanide (HCN) as the source of carbon and nitrogen for the synthesis of nucleotide, amino acid and lipid building blocks. HCN can be produced during impact events by reprocessing of carbonaceous and nitrogenous materials from both the impactor and the atmosphere; it can also be produced from these materials by electrical discharge. Here we investigate the effect of high energy events on a range of starting mixtures representative of various atmosphere-impactor volatile combinations. Using continuously scanning time–resolved spectrometry, we have detected ·CN radical and excited CO as the initially most abundant products. Cyano radicals and excited carbon monoxide molecules in particular are reactive, energy-rich species, but are resilient owing to favourable Franck–Condon factors. The subsequent reactions of these first formed excited species lead to the production of ground-state prebiotic building blocks, principally HCN.
“…Moreover, spectroscopic measurements performed on the dc electric glow in N 2 spectrum showed that although numerous molecular bands appear, nitrogen atomic lines are not present. Besides, the second positive system of N 2 and the first negative system of N (7,5) of N 2 (C-B). The upper panel of figure 7(a) shows the LIDB emission spectrum of nitrogen in the spectral region 2925-3175Å of nitrogen.…”
Section: Identification Of the Chemical Species In The Laser-induced mentioning
confidence: 99%
“…The LIDB nitrogen spectrum recorded by Babankova and co-workers [7] in the spectral region 300-700 nm is composed of one broadband formed from unresolved lines of N + and from the v = 0 − v = 0 electronic transition of N + 2 (B 2 + u -X 2 + g band system). The LIDB spectra from N 2 reported by Nordstrom [8] and Hanafi et al [9] are composed of N and N + atomic lines without identification of any molecular emission.…”
Large-scale plasma produced in nitrogen gas at room temperature and pressures ranging from 4 × 10 3 to 1.2 × 10 5 Pa by high-power laserinduced dielectric breakdown (LIDB) has been investigated. Time-integrated optical nitrogen gas spectra excited from a CO 2 laser have been measured and analysed. The spectrum of the generated plasma is dominated by the emission of strong N + and N and very weak N 2+ atomic lines and molecular features of N (B-X) systems are very weak as compared with the chemiluminescence spectrum of nitrogen formed in a glow discharge. An excitation temperature T exc = 21 000 ± 1300 K was calculated by means of the relative intensity of ionized nitrogen atomic lines assuming local thermodynamic equilibrium. Optical breakdown threshold intensities in N 2 at 9.621 µm have been determined. The physical processes leading to the LIDB of nitrogen in the power density range 0.4 < J < 4.5 GW cm −2 have been analysed. From our experimental observations we can suggest that, although the first electrons must appear via multiphoton ionization or natural ionization, electron cascade is the main mechanism responsible for the LIDB in nitrogen.
“…Such a period does not take place in the gas puff because the LIDB plasma expands through the thin layer of helium directly into vacuum. Experiments with the gas puff also provide the unique opportunity to look through the vacuum and observe the short-wavelength emission of LIDB plasma (Babankova et al 2006b, Figure 2). This cannot be done in the static cell due to strong absorption of short-wavelength radiation in the cold, dense gas.…”
Abstract. Large laser sparks created by a single shot of a high-power laser system were used for the laboratory simulation of the chemical consequences of high-energy-density events (lightning, high-velocity impact) in planetary atmospheres, e.g., the early Earth's atmosphere.Keywords. Astrobiology, astrochemistry, plasmas, methods: laboratory, techniques: spectroscopic It is currently a generally accepted opinion that Earth's early atmosphere was a mildly reduced mixture of molecular gases. This represents a crucial difficulty for the classical Miller's experiments. These experiments were carried out in a strongly reducing gaseous mixture. In a weakly reducing environment they give a poor yield of amino acids and other compounds of relevance to chemical evolution. In our study we intended to simulate impact shocks and lightning in the mixtures of molecular gases modeling Earth's early atmosphere with help of a focused beam from high-power laser systems (Civis et al. 2004, Babankova et al. 2006a and references cited therein). The main goal of this program is to diagnose the laser-produced plasma, determine its basic physical characteristics, and investigate their links to the chemical action of the laser spark in such a reaction system. Varying laser-plasma interaction conditions and composition of the gas mixtures of the chemical evolution during various stages of Earth's early atmosphere evolution was investigated in dependence on the kind and energetics of the initializing high-energy density event (i.e., impact shocks and atmospheric discharges).A single laser pulse delivered from a Prague Asterix Laser System (a pulse duration of 400 ps and a wavelength of 1.315 µm) with energy content 100 J was used for irradiation of the CO-N 2 -H 2 O gas mixtures (mildly reducing systems) and their components at atmospheric pressure. The high pulse energy and the relatively short pulse duration result in the observed large volume of the laser spark.Chemical consequences of the laser-produced plasma generation in such a gaseous system were investigated by gas/liquid chromatography and high-resolution Fourier transform infrared absorption spectrophotometry with a Bruker IFS 120 in the spectral interval from 500-7000 cm −1 at a resolution of 0.0035 cm −1 . Several organic compounds were identified in the reaction mixture exposed to a few laser shots. The reaction mechanism of CO 2 formation was investigated using stable isotope-labeled water H 18 2 O (Figure 1). Optical emission spectra (OES) of the large laser spark were measured by a MS255 spectrometer (Oriel) equipped with time-resolved ICCD detector (Andor) in the spectral range of 350-1000 nm. A significant difference has been found in the optical spectra of LIDB plasmas created in CO and N 2 containing mixtures in the static cell and gas puff (Babankova et al. 2006b). In the case of the jet, there is no examined emission from 473 available at https://www.cambridge.org/core/terms. https://doi
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