JCE Online Journal of Chemical Education
 | Subscriptions  | Software Orders  | Support  | Contributors  | Advertisers  | 

JCE Print
   Current Issue
 Previous Issues
 Supplements
 Search JCE Index

JCE Digital Library
   DigiDemos
 QBank
 SymMath
 WebWare

JCE Software
   Latest Releases
 Software & Video
 Downloads
 Support

Only@JCE Online
   JCE Online Store
 JCE HS CLIC
 JCE Discussion Forums
   Biographical Snapshots
 ChemEd Resource Shelf
 Featured Molecules
 Hal's Picks
 Project Chemlab
 Reviewed WWW Sites
 "Web-Ed" Articles

About JCE
   Features
 Publications
 Operations
 Outreach
 Contact Us


  Home > JCE Print > Journal of Chemical Education > Issues > 2005  > February  >
In the Laboratory
Halide (Cl–) Quenching of Quinine Sulfate Fluorescence: A Time-Resolved Fluorescence Experiment for Physical Chemistry
Jonathan H. Gutow
Department of Chemistry, University of Wisconsin–Oshkosh, Oshkosh, WI 54901
Cover
February 2005
Vol. 82 No. 2
p. 302
Abstract
A time-resolved fluorescence experiment for use in physical chemistry is described. Students investigate the halide quenching of the fluorescence from quinine sulfate in water (similar to tonic water). The students are able to determine that the fluorescence is quenched dynamically by collision with the halide, not by forming an equilibrated complex. Students reproduce the literature unquenched lifetime of about 19 ns and observe a nearly diffusion-limited collisional quenching rate of 5.2 × 109 M–1 in 0.5 M H2SO4. The experiment is popular with the students. The samples are easy to handle. It provides the students experience with modern equipment (lasers, fast data collection, and computer data analysis), while also requiring the students to review and use knowledge of the kinetics of competing processes and electronic spectroscopy. Samples of different concentration are divided among the students for analysis; in this manner nine students can complete the data collection for the experiment in one three-hour laboratory using a single fluorescence apparatus. If time resolution is not available this experiment can still be performed using intensity measurements. The quenching yields linear Stern–Volmer plots with a Ksv ≈107 M–1.
Supplement
Detailed instructions for the students and notes for the instructor are available.
*  Contents JCE2005p0302W.doc (Microsoft Word)
*  Download
JCE2005p0302W.pdf

JCE2005p0302W.zip

JCE2005p0302W.sit
More Information
*  Citation
 Gutow, Jonathan H. J. Chem. Educ. 2005 82 302.
*  Keywords
 Excited States / Energy Transfer; Kinetics; Laboratory Computing / Interfacing; Laboratory Instruction; Lasers / Laser Spectroscopy; Luminescence; Mechanisms of Reactions; Physical Chemistry; spectrometry*
*  History
 Created:
Last Updated:		 January 4, 2005
January 12, 2005
<< Previous Article Table of Contents Next Article >>
  Home > JCE Print > Journal of Chemical Education > Issues > 2005  > February  > Page 302


Subscriptions
 Subscription Info
 Order Forms

JCE HS CLIC

Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
 JCE HS CLIC

Contributions Welcome
JCE welcomes your submission
 Contributors' Corner

Advertisers
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.
 Recent Advertisers

Be An Ambassador
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.
 Outreach with JCE

Comments to
jceonline@chem.wisc.edu		 Copyright © Division of Chemical Education, Inc., American Chemical Society.
All rights reserved.