Intro to UV-Vis Molecular Absorption Spectrometry Chap 13

Instrument Components

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

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

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

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

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

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.

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

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.

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

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

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

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

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

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