{"id":2359,"date":"1985-11-03T15:54:27","date_gmt":"1985-11-03T21:54:27","guid":{"rendered":"https:\/\/kermitmurray.com\/murray\/?p=2359"},"modified":"2021-10-15T20:50:33","modified_gmt":"2021-10-16T01:50:33","slug":"methylene-st-splitting-by-photoelectron-spectroscopy","status":"publish","type":"post","link":"https:\/\/kermitmurray.com\/research\/1985\/11\/methylene-st-splitting-by-photoelectron-spectroscopy\/","title":{"rendered":"Methylene: A study of the X\u0303\u20093B1 and \u00e3\u20091A1 states by photoelectron spectroscopy of CH2\u2212and CD2\u2212"},"content":{"rendered":"\n
<\/div>
<\/div><\/div>
\n
<\/div>
<\/div><\/div>
\n

D.G. Leopold, K.K. Murray, A.E.S. Miller, W.C. Lineberger, Methylene: A study of the X\u0303\u20093<\/sup>B1<\/sub> and \u00e3\u20091<\/sup>A1<\/sub> states by photoelectron spectroscopy of CH2<\/sub>\u2212<\/sup>and CD2<\/sub>\u2212<\/sup>, J. Chem Phys.<\/em> 83<\/strong> (1985) 4849. doi:10.1063\/1.449746<\/a>.<\/p>\n\n\n\n

Abstract<\/h4>\n\n\n\n
\"Apparatus<\/a>
Apparatus from Leopold, Murray, Miller and Lineberger, J. Chem. Phys. 83, 4849 (1985).<\/figcaption><\/figure><\/div>\n\n\n\n

Photoelectron spectra are reported for the CH2<\/sub>(X<\/em>\u0303\u20093<\/sup>B<\/em>1<\/sub>)+e<\/em>\u2212<\/sup>\u2190CH\u2212<\/sup>2<\/sub> (X<\/em>\u0303\u20092<\/sup>B<\/em>1<\/sub>) and CH2<\/sub>(a<\/em>\u0303\u20091<\/sup>A<\/em>1<\/sub>)+e<\/em>\u2212<\/sup>\u2190CH\u2212<\/sup>2<\/sub>(X<\/em>\u0303\u20092<\/sup>B<\/em>1<\/sub>) transitions of the methylene and perdeuterated methylene anions, using a new flowing afterglow photoelectron spectrometer with improved energy resolution (11 meV). Rotational relaxation of the ions to \u223c300 K and partial vibrational relaxation to <1000 K in the flowing afterglow negative ion source reveal richly structured photoelectron spectra. Detailed rotational band contour analyses yield an electron affinity of 0.652\u00b10.006 eV and a singlet\u2013triplet splitting of 9.00\u00b10.09 kcal\/mol for CH2<\/sub>. (See also the following paper by Bunker and Sears<\/a>.) For CD2<\/sub>, results give an electron affinity of 0.645\u00b10.006 eV and a singlet\u2013triplet splitting of 8.98\u00b10.09 kcal\/mol. Deuterium shifts suggest a zero point vibrational contribution of 0.27\u00b10.40 kcal\/mol to the observed singlet\u2013triplet splitting, implying a T<\/em>e<\/em><\/sub> value of 8.7\u00b10.5 kcal\/mol. Vibrational and partially resolved rotational structure is observed up to \u223c9000 cm\u22121<\/sup> above the zero point vibrational level of the 3<\/sup>B<\/em>1<\/sub> states, revealing a previously unexplored region of the quasilinear potential surface of triplet methylene. Approximately 20 new vibration\u2010rotation energy levels for CH2<\/sub> and CD2<\/sub> are measured to a precision of \u223c30 cm\u22121<\/sup> in the v<\/em>2<\/sub>=2\u20137 region (bent molecule numbering). Bending vibrational frequencies in the methylene anions are determined to be 1230\u00b130 cm\u22121<\/sup> for CH\u2212<\/sup> and 940\u00b130 cm\u22121<\/sup> for CD\u2212<\/sup>2<\/sub>, and the ion equilibrium geometries are bracketed. The measured electron affinity also provides values for the bond strength and heat of formation of CH\u2212<\/sup>2<\/sub>, and the gas phase acidity of CH3<\/sub>. A detailed description of the new flowing afterglow photoelectron spectrometer is given.<\/p>\n<\/div><\/div>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":868,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[130,5],"tags":[128],"class_list":["post-2359","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-colorado","category-publication","tag-anion","entry"],"_links":{"self":[{"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/posts\/2359","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/comments?post=2359"}],"version-history":[{"count":6,"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/posts\/2359\/revisions"}],"predecessor-version":[{"id":2811,"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/posts\/2359\/revisions\/2811"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/media\/868"}],"wp:attachment":[{"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/media?parent=2359"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/categories?post=2359"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kermitmurray.com\/research\/wp-json\/wp\/v2\/tags?post=2359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}