Main

November 13, 2012

Paper to Read for 11/14/2012

Please read this paper for in-class discussion on Wednesday.

A great resource on this topic is http://www.microscopyu.com/articles/superresolution/index.html.

Here are the discussion questions:
1. What is the diffraction limit and why do we want to overcome it?
2. What is a photoswitching molecule?
3. Why are they critically important for sub-diffraction fluorescence imaging?
4. How is a diffraction-limited signal converted into a sub-diffraction image?
5. Why is the emission maximum red-shifted from the absorption maximum?
6. Describe the 3 major classes of photoswitchable dyes discussed here.
7. What experiment would you pursue using sub-diffraction fluorescence imaging?

October 25, 2012

"Background Correction in Atomic Absorption Utilizing the Zeeman Effect"

Please read this paper for in-class discussion on 10/29/2012.

Discussion Questions:

1. Why is background correction so important when using a furnace as the atomizer?
2. What is meant in the statement, "...possibility of inaccurate correction if the background is structured..."? Why is a continuum source background correction insufficient in this case?
3. The authors state that one of their goals in this work is to "... indicate how implementation of the Zeeman effect influences such factors as sensitivity and analytical range for many of the commonly determined elements." Summarize their results related to this goal.
4. Are the sensitivity trends the same for normal and anomalous Zeeman splitting? Why or why not?
5. Why does hyperfine structure (splitting of different J values) influence Zeeman corrected sensitivity?
6. Why is the artificial seawater sample matrix so disadvantageous when using continuum source background correction? Why is the Zeeman corrected spectrum improved?
7. What is the role of the monochromator's spectral bandpass in both continuum source and Zeeman corrected AA spectra?
8. Compare and contrast the three methods used to perform Zeeman correction: DC magnet around the atomizer, AC magnet around the atomizer, and DC magnet around the hollow cathode lamp.

September 17, 2012

Lasers

Before Wednesday's class, please read this perspective on lasers in analytical chemistry: "25 years of lasers and analytical chemistry: A reluctant pairing with a promising future" by Ben Smith. After reading, explore how one of the following methods work (according to the first letter of your last name): laser induced breakdown spectroscopy (A-H), laser ablation sampling (I-Q), or laser ionization mass spectrometry (R-Z).

**There will be no new notes for Wednesday's lecture - we will just finish the notes posted for Monday.