Nearhyphen;Resonant Electronic Energy Transfer from Argon to Hydrogen

摘要

The argon sensitized fluorescence of molecular hydrogen has been observed. Relative cross sections have been determined for transitions of the typeH2lpar;Xthinsp;1Sgr;gplus;,thinsp; vequals;0,thinsp;Jrpar; plus;Ar*rarr;H2lpar;Bthinsp;1Sgr;uplus;,thinsp; vprime;,thinsp;Jprime;rpar; plus;Arplus; Dgr; E,where Ar*is either Ar4slsqb;112rsqb;Jequals;10orArthinsp;4sprime;lsqb;12rsqb;Jequals;10and the hydrogen molecules, H2, D2, and HD are initially thermally distributed amongJstates at300 plusmn; 30deg;K. Calculations indicate that the largest cross sections, on the order of gas kinetic or larger, are due primarily to long range dipolehyphen;dipole interactions. These cross sections are for transitions for whichverbar;thinsp; Dgr; Ethinsp; verbar;thinsp; lang; 100thinsp;cmminus;1whenDgr; J equiv; Jprime; minus; Jequals;plusmn; 1.The long range dipolar calculations establish an absolute magnitude scale for the cross sections. A curve crossing mechanism is possible for negative Dgr;Eand provides a plausible explanation for the remaining levels excited. Generally, only one vibrational level of the hydrogen molecule is excited by each argon state. This contrasts sharply with many previous sensitized excitation experiments in which most of the energetically accessible energy levels are excited.