9 UV/Vis Spectroscopy
9.1 Correlation between Wavelength of Absorbed
Radiation and Observed Color
Absorbed light
Observed (transmitted)
color
Wavelength [nm]
Corresponding color
400
violet
yellow-green
425
indigo blue
yellow
450
blue
orange
490
blue-green
red
510
green
purple
530
yellow-green
violet
550
yellow
indigo blue
590
orange
blue
640
red
blue-green
730
purple
green
9.2 Simple Chromophores
Chromophore Compound
Transition λ max [nm] ε max Solvent
C–H
CH 4
σ   σ*
122
strong gas
C–C
CH 3 –CH 3
σ   σ*
135
strong gas
C=C
CH 2 =CH 2
π   π*
162
15000 heptane
(CH 3 ) 2 C=C(CH 3 ) 2
π   π*
196
11500 heptane
C=C=C
CH 2 =C=CH 2
170
227
4000
630
C– – – C
HC– – – CH
173
6000 gas
n-C 5 H 11 –C– – – C–CH 3
178
196
222
10000
2000
160
hexane
C–Cl
CH 3 Cl
n  σ*
173
200 hexane
C–Br
n-C 3 H 7 Br
n  σ*
208
300 hexane
© The Author(s), under exclusive license to Springer-Verlag GmbH, DE,
part of Springer Nature 2020
E. Pretsch et al., Structure Determination of Organic Compounds,
https://doi.org/10.1007/978-3-662-62439-5_9
445