仪器分析作业2

1. Attach names corresponding to the physical processes represented by arrows in

the following drawing of the energy levels in a diatomic molecule.

2. Sketch block diagrams for spectroscopic instruments involved in absorption and

fluorescence. Why are there differences between the two types of instruments?

3. How does absorption and emission of radiation by atoms differ from that absorbed

and emitted by molecules? Comment on the absorption spectrum of an atomic vapor versus a molecular vapor.

4. Describe some advantages of using inductively coupled plasma as an excitation

source compared to a flame for analytical spectroscopy?

5. A 50.0 mL aliquot of a quinine solution was diluted to 100.0 mL and found to

produce a relative fluorescent intensity of 0.832 at 348nm. A second 50.0 mL

aliquot was mixed with 10.0 mL of a solution containing 23.4 ppm of quinine and diluted to 100.0 mL. After dilution, the second solution was found to produce a relative fluorescent intensity of 1.220 at 348 nm. Calculate the concentration (in ppm) of quinine in the quinine solution.

6. Lithium in the blood serum of a manic-depressive patient treated with lithium

carbonate is determined by ICP emission spectrophotometry, using a standard addition method. One hundred microliters of serum is diluted to 1 mL giving an emission signal of 6.7 (relative units). A second serum sample is combined with 10 L of a 0.010M solution of LiNO3 and diluted to 1mL giving an emission signal of 14.6. Assuming linearity between the emission signal and lithium concentration, what is the concentration of lithium in the serum, in parts per million?

11.23这一周交作业。