A survey has been made of the systems used for the presentation of absorption spectra data in textbooks and journals. An attempt has been made to determine the accepted nomenclature systems, and recommendations have been made where there is some uncertainty as to proper or desirable form of presentation. Examples of data and graphical relation of values have been given to show the relative form of data as presented by different systems.
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I0 = Intensity of incident (or transmitted comparison) radiant energy.
T = Transmittance = I/I0 (Transmittancy is used to indicate relative transmittance if I0 is the transmitted comparison radiant energy).
t = Transtnissivity, (T−cd) is the Transmittance for a unit concentration and thickness.
%T = percent transmittance = T×100.
Absorption
Absorption law: I = I010−kcd
A = Absorbance = kcd = log10I0/I.
k = Absorptivity = A/cd (specific absorbance or absorbance per unit concentration and thickness).
∊ = Molar Absorptivity = k·M.
c = concentration in grams per liter, d = thickness of cell in cm,
M = molecular weight.
General The suffix -ion is used to indicate a process, as in the case of conduction or calibration; -or or -er to indicate a device as in generator or absorber; -ance to indicate a measurable quantity of a property such as resistance or conductance; and -ity to indicate a specific property of the measured substance such as density and conductivity.
Table II
Notation for absorption and transmission as used in textbooks.†
References to the authority cited here with the exception of the later group can be found in the bibliography section of W. R. Brode, Chemical Spectroscopy (John Wiley and Sons, Inc., New York, 1943), second edition.
See reference 8.
Table III
Absorption and transmission notation as used in current technical journals (approximately 1000 articles in 1946 to 1949).‡
Terms and symbols infrequently used have not been included. More than one system may be used in a single paper or graph. In 1949 approximately 15 percent of all articles in the J. Am. Chem. Soc. (200 out of 1300 as estimated from the first 9 months) contained absorption spectra data, as compared with a 5 percent absorption spectra content in 1936 in the same Journal. Note: In Tables III and V the notation used on absorption spectrographical forms has been recorded, rather than the notation used in the written text, since the former are usually more representative of the research workers’ ideas of presentation.
Indicates recommended notation.
Table IV
Wave-length units for recording absorption spectra.
Unit
Size of unit
Range (from left to right)
Region
1. Angstroms
meter ×10−10
1000 to 1A
Far or extreme-ultraviolet
2. mµ
meter ×10−9
1500 to 100 mµ
Ultraviolet and visible
3. mµ
meter ×10−9
400 to 750 mµ
Visible (color description)
4. μ
meter ×10−6
1 to 200μ
Infra-red and far-infra-red
5. cm
meter ×10−2
0.1 to 100 cm
Microwave
Table V
Wave-length, wave number, and frequency notation in applied technical literature (nearly 1000 articles from 1946 to 1949) for absorption spectra description. (Numbers indicate number of times used, * indicates authors recommended notation (see Tables IV and VI); (see ‡ note to Table III).
Names
No. times used
Symbols
No. times used
*Ultraviolet
270
*λ
124
Ultra violet
120
*A
12
Ultra-violet
30
Å
52
AU and IA
16
*Infrared
310
*mµ
438
Infra red
30
µµ
14
Infra-red
90
*μ
280
mmµ
6
*Wavelength
96
*ν
28
Wave length
370
*f
16
Wave-length
16
*ν′
12
1/λ
2
*Wavenumber
8
4
Wave number
60
σ
2
Wave-number
10
mm−1
16
*cm−1
106
*Frequency
44
*cm−1×10−2 or 10−3
10
mm−1
4
Table VI
Frequency and wave number units for recording absorption spectra.
I0 = Intensity of incident (or transmitted comparison) radiant energy.
T = Transmittance = I/I0 (Transmittancy is used to indicate relative transmittance if I0 is the transmitted comparison radiant energy).
t = Transtnissivity, (T−cd) is the Transmittance for a unit concentration and thickness.
%T = percent transmittance = T×100.
Absorption
Absorption law: I = I010−kcd
A = Absorbance = kcd = log10I0/I.
k = Absorptivity = A/cd (specific absorbance or absorbance per unit concentration and thickness).
∊ = Molar Absorptivity = k·M.
c = concentration in grams per liter, d = thickness of cell in cm,
M = molecular weight.
General The suffix -ion is used to indicate a process, as in the case of conduction or calibration; -or or -er to indicate a device as in generator or absorber; -ance to indicate a measurable quantity of a property such as resistance or conductance; and -ity to indicate a specific property of the measured substance such as density and conductivity.
Table II
Notation for absorption and transmission as used in textbooks.†
References to the authority cited here with the exception of the later group can be found in the bibliography section of W. R. Brode, Chemical Spectroscopy (John Wiley and Sons, Inc., New York, 1943), second edition.
See reference 8.
Table III
Absorption and transmission notation as used in current technical journals (approximately 1000 articles in 1946 to 1949).‡
Terms and symbols infrequently used have not been included. More than one system may be used in a single paper or graph. In 1949 approximately 15 percent of all articles in the J. Am. Chem. Soc. (200 out of 1300 as estimated from the first 9 months) contained absorption spectra data, as compared with a 5 percent absorption spectra content in 1936 in the same Journal. Note: In Tables III and V the notation used on absorption spectrographical forms has been recorded, rather than the notation used in the written text, since the former are usually more representative of the research workers’ ideas of presentation.
Indicates recommended notation.
Table IV
Wave-length units for recording absorption spectra.
Unit
Size of unit
Range (from left to right)
Region
1. Angstroms
meter ×10−10
1000 to 1A
Far or extreme-ultraviolet
2. mµ
meter ×10−9
1500 to 100 mµ
Ultraviolet and visible
3. mµ
meter ×10−9
400 to 750 mµ
Visible (color description)
4. μ
meter ×10−6
1 to 200μ
Infra-red and far-infra-red
5. cm
meter ×10−2
0.1 to 100 cm
Microwave
Table V
Wave-length, wave number, and frequency notation in applied technical literature (nearly 1000 articles from 1946 to 1949) for absorption spectra description. (Numbers indicate number of times used, * indicates authors recommended notation (see Tables IV and VI); (see ‡ note to Table III).
Names
No. times used
Symbols
No. times used
*Ultraviolet
270
*λ
124
Ultra violet
120
*A
12
Ultra-violet
30
Å
52
AU and IA
16
*Infrared
310
*mµ
438
Infra red
30
µµ
14
Infra-red
90
*μ
280
mmµ
6
*Wavelength
96
*ν
28
Wave length
370
*f
16
Wave-length
16
*ν′
12
1/λ
2
*Wavenumber
8
4
Wave number
60
σ
2
Wave-number
10
mm−1
16
*cm−1
106
*Frequency
44
*cm−1×10−2 or 10−3
10
mm−1
4
Table VI
Frequency and wave number units for recording absorption spectra.