Please post this week's minute papers as "comments" to this post. Minute papers should be posted by 5 pm on Friday. Feel free to read your classmate's posts.
There are two portions to problem set #3.
In the original syllabus, there was no class scheduled for Friday, November 20th. In fact, class will meet that day.
The due date for problem set #3 will be 11/11/2009 rather than 11/04/2009 as stated in the syllabus.
There is an Analytical Chemistry A-Pages article to read for the atomic fluorescence spectroscopy section of class.
You should read "Sub-Part-per-Billion Analysis of Aqueous Lead Colloids by ArF Laser Induced Atomic Fluorescence" by S. K. Ho and coworkers before class on 11/02/09.
Discussion Questions:
1. What is colloidal lead?
2. Why is the spectral background significantly reduced when using atomic fluorescence compared to this group's earlier laser-induced plasma spectroscopy experiment?
3. The excitation wavelength is 193 nm while the main fluorescence is at 405.8 nm. Identify the type of fluorescence observed in this work.
4. Why does the colloid size influence the signal strength?
5. Why couldn't the authors use their original calibration curve when analyzing tap water? What advantage do they gain by using standard addition instead?
6. How would AES or AAS analysis of the lead colloid samples compare to the work presented herein?
Please post this week's minute papers as "comments" to this post. Minute papers should be posted by 5 pm on Friday. Feel free to read your classmate's posts.
I've included missing slides from Wednesday's lectures in the notes posted for Lecture 20.
On Monday, we will finish the notes you already have and go over the answers for exam 1.
Please read this paper for in-class discussion on 10/28/09.
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.
Exam #1 is tomorrow, October 23rd, from 3:30-5:30 pm in Smith 111. Please bring a pencil, scientific calculator, and an equation sheet (as detailed in the syllabus).
Please post this week's minute papers as "comments" to this post. Minute papers should be posted by 12 pm on Sunday (this week only). Feel free to read your classmate's posts.