1. Intro to UV-Vis Molecular Absorption Spectrometry
Chap 13

2. Instrument Components

3. (1) Common Sources for the UV-Vis
Deuterium Lamp
Emission spectrum

4. (1) Common Sources for the UV-Vis
Tungsten Lamp
Emission spectrum

5. (1) Common Sources for the UV-Vis
Output intensities of a D2 lamp (UV)
and a W lamp (Vis) at 3200K.

6. (2) Wavelength Selectors (Filters)
Figure 7-16
(FWHM)
Interference Filter:
narrow bandpass
∼ 10 nm
Absorption Filter:
wide bandpass ∼ 50 nm

7. (2) Wavelength Selectors (Absorption Filters)
Colors of Visible Light

8. Newton’s Color Wheel The color absorbed is the complement of the
color of a solution itself:
e.g., A soln. of FeSCN2+ is red
because green is absorbed,
∴ a green filter is employed.

9. (2) Wavelength Selectors (Monochromator)
Schematic of a Czerny-Turner Monochromator
Figure 7-18 (a)

10. Principle of a Reflection Grating.
Figure 7-21
Constructive interference when reflected light is in phase.
Destructive interference when reflected light is 180o out-of-phase.

11. Effect of Slit Width on Spectral Detail of Benzene Vapor
Figure 13-8

12. Monochromator Slit Widths Figure 7-25 Wide slits high Abs but low res.
good for quant. work
Narrow slits
high res but low Abs.
good for qual. work

13. Photomultiplier tube (PMT)
(3) Detectors (PMT)
Figure 7-31
Photomultiplier tube (PMT)

14. (3) Detectors (Photodiode Array)
Figure 7-32 (a)
Silicon diode

15. (3) Detectors (Photodiode Array)
Figure 7-32 (b)
Silicon diode – Reverse bias

16. (3) Detectors (Photodiode Array)
Figure 13-15
All λ’s measured simultaneously.