From chemistry-request@ccl.net Sun Oct 19 23:00:06 2003 Received: from mercury.chem.pitt.edu (mercury.chem.pitt.edu [136.142.60.100]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h9K2xXMV009398 for ; Sun, 19 Oct 2003 22:59:33 -0400 Received: from ringo.chem.pitt.edu (localhost.localdomain [127.0.0.1]) by mercury.chem.pitt.edu (Postfix) with SMTP id 0F16D483D for ; Sun, 19 Oct 2003 22:28:32 -0400 (EDT) Received: from 200.97.135.57 (SquirrelMail authenticated user gustavo) by mercury.chem.pitt.edu with HTTP; Sun, 19 Oct 2003 22:28:32 -0400 (EDT) Message-ID: <2763.200.97.135.57.1066616912.squirrel$at$mercury.chem.pitt.edu> Date: Sun, 19 Oct 2003 22:28:32 -0400 (EDT) Subject: Absorption Cross Section From: To: X-Priority: 3 Importance: Normal X-Mailer: SquirrelMail (version 1.2.11) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=0.8 required=7.0 tests=NO_REAL_NAME version=2.55 X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-exp) Dear CCL readers, I have read several papers about the calculation of the cross sections for two-photon absorption (d). The value of d as a function of the frequency of the incident photon (w) is related to the imaginary part of the second hyperpolarizability gamma(-w;w,w,-w) through d=(8*pi^2*hbar*w^2)/(n*c)^2*Im[gamma(-w;w,w,-w)] where n is a refractive index and c is the speed of light. None of the papers I have read so far say where the equation above came from. So my question is: Does anybody on this list know the origin of the equation above? Reference? I am also curious to know if there is a similar equation relating the imaginary part of the polarizability alpha(-w;w) to a cross section for one-photon absorption. Is this cross section simply the oscillator strength for the one photon transition? Thank you very much in advance. I will summarize if I receive any answer. Gustavo Moura gustavo^at^mercury.chem.pitt.edu From jkl@ccl.net Mon Oct 20 06:05:03 2003 -0400 Return-Path: Message-Id: <5.0.2.1.0.20031020120614.00a60cf0*at*mail.tiscalinet.ch> Date: Mon, 20 Oct 2003 12:08:32 +0200 To: chemistry*at*ccl.net From: Barry Hardy Subject: Bursaries/Poster session, eCheminformatics 2003 I enclose information on the eCheminformatics 2003 Poster Session and the availability of Young Investigator Bursaries. All accepted Posters will be eligible for the eCheminformatics 2003 Best Poster Award, as judged by our Speaker panel. Young Investigator Bursaries available to attend eCheminformatics 2003 We have available a number of bursaries for young academic investigators to attend the eCheminformatics 2003 virtual conference http://conferences.metalayer.net/echeminfo/ Bursary awards will include a waiver of the conference registration fee. All research investigators under the age of 35 are eligible to receive a bursary. Candidates should submit an abstract for a Conference Poster by 24th October 2003 accompanied by supporting materials (CV, publication or presentation references) to Dr. Barry Hardy, barry.hardy*at*tiscalinet.ch Poster Session All conference registrants have the opportunity to present a conference Poster on a cheminformatics subject during the conference. Posters can be presented in Word, pdf, html or Powerpoint format. If you wish to present a Poster at the conference, please submit your abstract to us with Title, author(s), institution, contact email address, contact phone number and abstract of no more than 300 words. Registrants will subsequently be able to directly upload their poster to the Poster Session area of the Conference site. The deadline for receipt of Poster Abstracts is the 24th October. Barry Hardy Conference Secretariat barry.hardy*at*tiscalinet.ch +41 61 851 0170