ERIC Number: EJ913391
Record Type: Journal
Publication Date: 2010-Apr
Pages: 4
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-0021-9584
EISSN: N/A
Surface-Enhanced Resonance Raman Scattering and Visible Extinction Spectroscopy of Copper Chlorophyllin: An Upper Level Chemistry Experiment
Schnitzer, Cheryl S.; Reim, Candace Lawson; Sirois, John J.; House, Paul G.
Journal of Chemical Education, v87 n4 p429-432 Apr 2010
Advanced chemistry students are introduced to surface-enhanced resonance Raman scattering (SERRS) by studying how sodium copper chlorophyllin (CuChl) adsorbs onto silver colloids (CuChl/Ag) as a function of pH. Using both SERRS and visible extinction spectroscopy, the extent of CuChl adsorption and colloidal aggregation are monitored. Initially at pH[is asymptotically equivalent to]10, the colloids possess an overall negative surface charge, preventing attraction. Surface-enhanced Raman scattering (SERS) is not detected at that pH because the relatively small colloids do not possess a surface plasmon in resonance with the laser excitation frequency (633 nm). Once the solution pH decreases slightly, colloidal clusters form and SERRS is detected. As the pH is lowered to a value of 4 or 3, protonation of CuChl results in colloidal aggregation and precipitation. If adsorption and aggregation are halted by adding H[subscript 2]SO[subscript 4](aq) and then NaOH(aq), an intense SERRS signal is steadily detected from acidic pH (about 4), back to the initial basic pH (about 10). (Contains 3 figures.)
Descriptors: Spectroscopy, Chemistry, Science Experiments, Advanced Students, Undergraduate Students, College Science, Science Instruction, Science Activities
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Publication Type: Journal Articles; Reports - Evaluative
Education Level: Higher Education; Postsecondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A