{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,4]],"date-time":"2026-10-04T11:01:44Z","timestamp":1791111704204,"version":"4.1.0"},"reference-count":33,"publisher":"American Association for the Advancement of Science (AAAS)","issue":"5311","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Science"],"published-print":{"date-parts":[[1997,4,18]]},"abstract":"<jats:p>\n            Laboratory simulations of shocks created with a high-energy laser demonstrate that the efficacy of organic production depends on the molecular, not just the elemental composition of the shocked gas. In a methane-rich mixture that simulates a low-temperature equilibrium mixture of cometary material, hydrogen cyanide and acetylene were produced with yields of 5 \u00d7 10\n            <jats:sup>17<\/jats:sup>\n            molecules per joule. Repeated shocking of the methane-rich mixture produced amine groups, suggesting the possible synthesis of amino acids. No organic molecules were produced in a carbon dioxide\u2013rich mixture, which is at odds with thermodynamic equilibrium approaches to shock chemistry and has implications for the modeling of shock-produced organic molecules on early Earth.\n          <\/jats:p>","DOI":"10.1126\/science.276.5311.390","type":"journal-article","created":{"date-parts":[[2002,7,27]],"date-time":"2002-07-27T09:39:52Z","timestamp":1027762792000},"page":"390-392","source":"Crossref","is-referenced-by-count":100,"title":["Organic Synthesis in Experimental Impact Shocks"],"prefix":"10.1126","volume":"276","author":[{"given":"Christopher P.","family":"McKay","sequence":"first","affiliation":[{"name":"Space Science Division, NASA Ames Research Center, Moffett Field, CA 94035, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William J.","family":"Borucki","sequence":"additional","affiliation":[{"name":"Space Science Division, NASA Ames Research Center, Moffett Field, CA 94035, USA."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"221","reference":[{"key":"e_1_3_1_2_2","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1038\/277123a0","volume":"277","author":"Chameides W. L.","year":"1979","unstructured":"Chameides W. L., Nature 277, 123 (1979);","journal-title":"Nature"},{"key":"e_1_3_1_2_3","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1029\/RG022i004p00363","volume":"22","author":"Borucki W. J.","year":"1984","unstructured":"Borucki W. J., Chameides W. L, Rev. Geophys. Space Phys. 22, 363 (1984).","journal-title":"Rev. Geophys. Space Phys."},{"key":"e_1_3_1_3_2","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1038\/319305a0","volume":"319","author":"Fegley B.","year":"1986","unstructured":"Fegley B., Prinn R. G., Hartman H., Watkins G. H., Nature 319, 305 (1986).","journal-title":"Nature"},{"key":"e_1_3_1_4_2","doi-asserted-by":"crossref","unstructured":"W. L. Chameides and J. C. G. Walker Origins Life 11 291 (1981).","DOI":"10.1007\/BF00931483"},{"key":"e_1_3_1_5_2","first-page":"215","volume":"190","author":"Lewis J. S.","year":"1982","unstructured":"Lewis J. S., Watkins G. H., Hartman H., Prinn R. G., Geol. Soc. Am. Spec. Pap. 190, 215 (1982).","journal-title":"Geol. Soc. Am. Spec. Pap."},{"key":"e_1_3_1_6_2","doi-asserted-by":"crossref","first-page":"520","DOI":"10.1038\/332520a0","volume":"332","author":"McKay C. P.","year":"1988","unstructured":"McKay C. P., Scattergood T. R., Pollack J. B., Borucki W. J., Van Ghyseghem H. T., Nature 332, 520 (1988).","journal-title":"Nature"},{"key":"e_1_3_1_7_2","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1016\/0019-1035(89)90061-4","volume":"81","author":"Scattergood T. R.","year":"1989","unstructured":"Scattergood T. R., et al., Icarus 81, 413 (1989).","journal-title":"Icarus"},{"key":"e_1_3_1_8_2","first-page":"125","volume":"76","author":"Borucki W. J.","year":"1988","unstructured":"Borucki W. J., Giver L. P., McKay C. P., Scattergood T. R., Parris J. E., ibid. 76, 125 (1988).","journal-title":"ibid."},{"key":"e_1_3_1_9_2","doi-asserted-by":"crossref","first-page":"755","DOI":"10.1038\/326755a0","volume":"326","author":"Kissel J.","year":"1987","unstructured":"Kissel J., Krueger F. R., Nature 326, 755 (1987).","journal-title":"Nature"},{"key":"e_1_3_1_10_2","unstructured":"S. Gordon and B. J. McBride Computer Program for Calculation of Complex Chemical Equilibrium Compositions Rocket Performance Incident and Reflected Shocks and Chapman-Jouguet Detonations NASA SP-273 (U.S. Government Printing Office Washington DC 1971)."},{"key":"e_1_3_1_11_2","unstructured":"The CH 4 -containing mixture was 42% H 2 O 29% CO 2 22% CH 4 and 4.3% N 2 . The gases other than water were obtained as premixed research-grade gases. This gas was added to the correct amount of distilled water in a 250-ml glass flask to achieve the final mixture. The sample flasks and the controls were placed within an oven held at 80\u00b0C such that all the water was in vapor form."},{"key":"e_1_3_1_12_2","unstructured":"Typically the beam contained \u223c0.2 J in a pulse of \u223c15 ns repeated 10 times a second (6). A plasma formed when the laser beam was brought to a focus as first reported by P. D. Maker R. W. Terhune C. M. Savage [in Proceedings of the 3rd International Conference on Quantum Electronics Paris 11 to 15 February 1963 (Columbia Univ. Press New York 1964) vol. 2 pp. 1559\u20131576]. See also Yu."},{"key":"e_1_3_1_12_3","doi-asserted-by":"crossref","first-page":"650","DOI":"10.1070\/PU1966v008n05ABEH003027","volume":"8","author":"Raizer P.","year":"1966","unstructured":"Raizer P., Sov. Phys. Usp. 8, 650 (1966);","journal-title":"Sov. Phys. Usp."},{"key":"e_1_3_1_12_4","doi-asserted-by":"crossref","first-page":"1246","DOI":"10.1021\/ac00259a016","volume":"55","author":"Radziemski L. R.","year":"1983","unstructured":"Radziemski L. R., Loree T. R., Cremers D. A., Hoffman N. M., Anal. Chem. 55, 1246 (1983);","journal-title":"Anal. Chem."},{"key":"e_1_3_1_12_5","unstructured":"; D. D. Davis G. R. Smith W. A. Guillory Origins Life 10 237 (1980). The spectral properties and optical emission of the laser-induced plasma have been characterized (6 13 23 24). For gas-phase analysis we used a 4-min exposure. The total energy deposited is sufficient to heat only about 15% of the gas to a freeze-out temperature of 2500 K. However some experiments were conducted in which the exposure time was increased to 20 min to allow for maximal processing of the mixture and the production of a solid residue. The laser output was directly measured with a bolometric power meter. None of the gaseous species in the experiment caused significant absorption at the 1.06-\u03bcm laser line over the short pathlengths (1 cm) used. The efficiency with which this power was converted to plasma energy was determined by direct measurement of the total power deposited in the test chamber as described (24)."},{"key":"e_1_3_1_13_2","unstructured":"Using spectroscopy we characterized the free electron concentration and gas temperature as the plasma cooled (13). The electron density dropped from 7 \u00d7 10 17 cm \u20133 at 0.6 \u03bcs after ignition to 0.9 \u00d7 10 17 cm \u20133 at 4.0 \u03bcs after ignition. The electron temperature dropped from 17 000 to 12 000 K over this same interval."},{"key":"e_1_3_1_14_2","doi-asserted-by":"crossref","unstructured":"D. S. Jebens H. S. Lakkaraju C. P. McKay W. J. Borucki Geophys. Res. Lett. 19 273 (1992).","DOI":"10.1029\/91GL02937"},{"key":"e_1_3_1_15_2","doi-asserted-by":"crossref","unstructured":"K. Zahnle M. M. MacLow K. Lodders B. F. Fegley ibid. 22 1593 (1995).","DOI":"10.1029\/95GL01190"},{"key":"e_1_3_1_16_2","unstructured":"Spectral comparison of the temperature and pressure history of the laser plasma and natural lightning (12 13) indicated that at temperatures near the freeze-out (2000 to 3000 K) the trajectories on a pressure-temperature diagram are similar."},{"key":"e_1_3_1_17_2","unstructured":"The CH 4 -containing mixture products were determined with a Hewlett-Packard model 5992 GC-MS except for ethane and ethylene which were detected with a gas chromatograph with a metastable ion-drift detector. The mass difference between CO and N 2 could not be resolved so CO production could not be determined. Analysis was by GC-MS and by direct MS. Hydrocarbon compounds with a mass of >27 were difficult to distinguish because of the large amount of other gases present in the original mixture. The H 2 \u2013CO 2 mixtures were analyzed with a Varian 9600 gas chromatograph. Taking into account the variation in the amount of water entered into the sample and variations in the laser beam energy and flask transmission we conservatively estimated that our values are accurate to a factor of 2. Improved identification could be achieved if the parent gases are removed by cryogenic cooling. Samples and controls were kept shielded from sunlight and room light. No measurable production of organics was found in the controls."},{"key":"e_1_3_1_18_2","unstructured":"The solid residue was analyzed by solution in boiling dichloromethane and in methanol. No organic material was detected at a level of 1 ppm in the dichloromethane. The methanol solution examined with a Fourier Transform Infrared Spectrometer (IBM model 32) indicated the presence of soluble organic matter. Infrared absorption bands were identified at 2922 2855 and 1450 wavenumbers indicating the presence of aliphatic hydrocarbons; at 1516 wavenumbers indicating a small amount of aliphatic amine; at 1636 wavenumbers indicating an amide group; and at 1117 wavenumbers indicating the possible presence of alcohol groups. We could not accurately determine the yield of the solid residue because of the long exposure time required to produce this material and the resulting reprocessing of products. However based on the exposure time (20 min) and product amount (determined to be about 0.01 mg on the basis of concentrations in solution) we can estimate its yield at about 1% of the yield of the major hydrocarbons. An x-ray fluorescence spectrum of the solid residue showed a strong sulfur line indicating incorporation at the few percent level in the solid residue."},{"key":"e_1_3_1_19_2","unstructured":"We estimated the importance of UV production using the results of experiments in which the shock is isolated from the parent mixture by a UV transparent window (6). Yields of the main photolysis products with UV-only compared to yields with complete shocks were: 1 to 4% C 2 H 2 10 to 20% C 2 H 6 and 0.1 to 1% HCN. Our results correspond to similar yields for the UV production \u22431 to 10% of the total shock production is due to UV."},{"key":"e_1_3_1_20_2","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1086\/190963","volume":"55","author":"Yung Y. L.","year":"1984","unstructured":"Yung Y. L., Allen M., Pinto J. P., Astrophys. J. Suppl. Ser. 55, 465 (1984).","journal-title":"Astrophys. J. Suppl. Ser."},{"key":"#cr-split#-e_1_3_1_21_2.1","doi-asserted-by":"crossref","unstructured":"J. B. Pollack Y. L. Yung Annu. Rev. Earth Planet. Sci. 8 425 (1980)","DOI":"10.1146\/annurev.ea.08.050180.002233"},{"key":"#cr-split#-e_1_3_1_21_2.2","doi-asserted-by":"crossref","unstructured":"H. D. Holland The Chemical Evolution of the Atmosphere and Oceans (Princeton Univ Press Princeton NJ 1984).","DOI":"10.1515\/9780691220239"},{"key":"e_1_3_1_22_2","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1038\/340046a0","volume":"340","author":"Mukhin L. M.","year":"1989","unstructured":"Mukhin L. M., Gerasimov M. V., Safonova E. N., Nature 340, 46 (1989).","journal-title":"Nature"},{"key":"e_1_3_1_23_2","unstructured":"We can compare the expected yields for organics on early Earth with the other main production mechanism solar UV light. C. Chyba and C. Sagan [ Nature 355 125 (1992)] estimate that the solar UV produces 3 \u00d7 10 8 kg year \u22121 in a neutral atmosphere and 2 \u00d7 10 11 kg year \u22121 in a reducing atmosphere. For our CH 4 -containing mixture and using the atmospheric shock deposition rate estimated by Chyba and Sagan of 10 17 J year \u22121 we find an organic production of 3 \u00d7 10 10 kg year \u22121 . For the lightning rate of Chyba and Sagan 10 18 J year \u22121 the organic production is 3 \u00d7 10 11 kg year \u22121 ."},{"key":"e_1_3_1_24_2","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1016\/0019-1035(85)90087-9","volume":"64","author":"Borucki W. J.","year":"1985","unstructured":"Borucki W. J., McKenzie R. L., McKay C. P., Duong N. D., Boac D. S., Icarus 64, 221 (1985);","journal-title":"Icarus"},{"key":"e_1_3_1_24_3","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1038\/328509a0","volume":"328","author":"Borucki W. J.","year":"1987","unstructured":"Borucki W. J., McKay C. P., Nature 328, 509 (1987).","journal-title":"Nature"},{"key":"e_1_3_1_25_2","doi-asserted-by":"crossref","unstructured":"W. J. Borucki C. P. McKay R. S. Rogers D. S. Boac N. D. Duong J. E. Parris Appl. Opt. 26 4319 (1987).","DOI":"10.1364\/AO.26.004319"},{"key":"e_1_3_1_26_2","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1098\/rsta.1988.0064","volume":"325","author":"Delsemme A. H.","year":"1988","unstructured":"Delsemme A. H., Philos. Trans. R. Soc. London Ser. A 325, 509 (1988);","journal-title":"Philos. Trans. R. Soc. London Ser. A"},{"key":"e_1_3_1_26_3","unstructured":". Some 10% of the O 2 has been removed to account for oxides in the rock fraction of the cometary material as in D. Simonelli J. B. Pollack C. P. McKay R. T. Reynolds and A. L. Summers [ Icarus 82 1 (1989)]."},{"key":"e_1_3_1_27_2","unstructured":"This research was supported by subventions from the NASA Exobiology Program. We thank M. Carter of Carter Analytical Laboratories for performing the GC-MS analysis and for helpful discussions. GC analysis was performed by D. Kojiro F. Church and R. Quinn."}],"container-title":["Science"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.science.org\/doi\/pdf\/10.1126\/science.276.5311.390","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,1,13]],"date-time":"2024-01-13T04:45:08Z","timestamp":1705121108000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.science.org\/doi\/10.1126\/science.276.5311.390"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1997,4,18]]},"references-count":33,"journal-issue":{"issue":"5311","published-print":{"date-parts":[[1997,4,18]]}},"alternative-id":["10.1126\/science.276.5311.390"],"URL":"https:\/\/doi.org\/10.1126\/science.276.5311.390","relation":{},"ISSN":["0036-8075","1095-9203"],"issn-type":[{"value":"0036-8075","type":"print"},{"value":"1095-9203","type":"electronic"}],"subject":[],"published":{"date-parts":[[1997,4,18]]}}}