scholarly journals The absorption spectra of hexatriene and divinyl acetylene in the vacuum ultra-violet

1946 ◽  
Vol 185 (1001) ◽  
pp. 182-191 ◽  
Keyword(s):  
Double Bond ◽  
Ionization Potential ◽  
Absorption Spectra ◽  
Wave Length ◽  
Ultra Violet ◽  
Ionization Potentials ◽  
A Value ◽  
Integral Graphs ◽  
First Ionization Potential ◽  
Vacuum Ultra Violet

The absorption spectra of hexatriene and divinyl acetylene have been investigated in the region 2700-1200 A. In both molecules the longest wave-length regions of absorption are the strongest and these are interpreted as N → V 1 intravalence shell transitions. The spectra appear to be consistent with a value of about 8·2 V for the first ionization potential of hexatriene. Calculations based oh certain features of the spectra give reasonable values for the double-bond resonance integral. Graphs are given which enable the first regions of absorption and the ionization potentials of the higher polyenes to be predicted.

scholarly journals The absorption spectra of the cyclic dienes in the vacuum ultra-violet

1941 ◽  
Vol 179 (977) ◽  
pp. 201-214 ◽  
Keyword(s):  
Electronic Structure ◽  
Double Bond ◽  
Ionization Potential ◽  
Absorption Spectra ◽  
Ultra Violet ◽  
Ionization Potentials ◽  
Rydberg Series ◽  
Cyclic Dienes ◽  
Vacuum Ultra Violet ◽  
Marked Tendency

The absorption spectra of cyclohexadiene, cyclopentadiene, pyrrole, thiophene and furan have been investigated in the vacuum ultra-violet. The spectra obtained are due to the excitation of a π electron from the conjugated double-bond electrons (X 2 1 x 2 2 )• The ionization potentials of the molecules deduced from Rydberg series are respectively 8.4, 8.58, 8.9, 8.91 and 9.01V, these values referring to the outer X 2 shell of π electrons. A second less certain ionization potential of about 10.8V was obtained for furan. Some discussion of the electronic structure of the molecules on the basis of their spectra is given, and it is concluded that only in furan is there marked tendency towards homocyclic conjugation. It is also concluded that ‘hyperconjugation’ does not play so large a part in the interpretation of the spectra of cyclohexadiene and cyclopentadiene as previously supposed.

scholarly journals The absorption spectra of benzene derivatives in the vacuum ultra-violet. I

1947 ◽  
Vol 191 (1024) ◽  
pp. 22-31 ◽  
Keyword(s):  
Ionization Potential ◽  
Absorption Spectra ◽  
Ultra Violet ◽  
Benzene Derivatives ◽  
Rydberg Series ◽  
First Ionization Potential ◽  
Vacuum Ultra Violet

New photographs of the far ultra-violet spectrum of benzene are presented. The absorption from 2000 to 1800A ( λ max , c . 1980A) is regarded not as a part of the much stronger absorp­tion of peak at 1790A but as due to a separate transition. Sharp bands lying at 1790A represent the first member of a previously reported Rydberg series. The spectra of toluene, xylene, monochloro-and o -dichlorobenzene, bromobenzene, iodoben-zene and pyridine are briefly described, and the shifts relative to benzene are discussed. Two Rydberg series were observed for toluene, converging to a first ionization potential of 8.77 ± 0.05 V.

The far ultra-violet absorption spectra of the hydrides and deuterides of sulphur, selenium and tellurium and of the methyl derivatives of hydrogen sulphide

1950 ◽  
Vol 201 (1067) ◽  
pp. 600-609 ◽  
Keyword(s):  
Ionization Potential ◽  
Absorption Spectra ◽  
Ground State ◽  
Lone Pair ◽  
Ultra Violet ◽  
General Nature ◽  
Rydberg Series ◽  
Group Vi ◽  
Methyl Derivatives ◽  
First Ionization Potential

The absorption spectra in the vacuum ultra-violet of the hydrides and deuterides of sulphur, selenium and tellurium, and methyl mercaptan and dimethyl sulphide are described. Well-developed Rydberg series leading to the following ionization potentials have been found: H 2 S, 10.47V; MeSH, 9.44V; H 2 Se, 9.88V; H 2 Te, 9.14V. In the case of one series for H 2 Se fifteen members of the series were observed. The spectra of the deuterides are almost identical with those of the hydrides, showing that virtually every band in the spectra is due to a separate electronic transition. This and the general nature of the rotational fine structure show the transitions concerned to be those of an electron from a non-bonding ground-state orbital, i.e. from the p lone-pair ground-state orbital. The nature of the upper orbitals of the various series is also interpreted and shown to provide explanations of certain peculiarities of the observations. The quantity I(X) — J(H 2 X), where X is a group VI element, or I ( Y ) — I ( HY), where Y is a group VII element, is shown to be positive and comparatively large when X or Y lies in the first period of the periodic table, but to change sign and to remain almost constant at a small negative value as one passes to elements in later periods. A plot of I (H 2 X)against the first ionization potential of the corresponding inert gas is linear. Extrapolation enables the first ionization potential of H 2 Po to be predicted at 8.6V. A similar plot for the halogen acids, if assumed linear, yields a predicted first ionization potential for HF of 17.0±0.7V.

Electronic Levels of Methyl Amines by Photoelectron Spectroscopy and an i.n.d.o. Calculation

1971 ◽  
Vol 49 (7) ◽  
pp. 1135-1136 ◽  
Author(s):  
A. B. Cornford ◽  
D. C. Frost ◽  
F. G. Herring ◽  
C. A. McDowell
Keyword(s):  
Binding Energy ◽  
Ionization Potential ◽  
Photoelectron Spectroscopy ◽  
Lone Pair ◽  
Ionization Potentials ◽  
The One ◽  
First Ionization Potential

The ionization potentials of the methyl amines down to 20 eV binding energy, have been determined by photoelectron spectroscopy, and are compared with those predicted by i.n.d.o.-l.c.a.o.-s.c.f. theory. The first ionization potential for each compound refers to the removal of an electron from the lone pair, and is shown to be the one most affected by the inclusion of one center repulsion integrals in the i.n.d.o. calculations.

scholarly journals The absorption spectra of conjugated dienes in the vacuum ultra-violet (1)

1940 ◽  
Vol 174 (957) ◽  
pp. 220-234 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Electronic Structures ◽  
Spectroscopic Data ◽  
Ultra Violet ◽  
Conjugated Dienes ◽  
Strong Absorption ◽  
Absorption Bands ◽  
Lennard Jones ◽  
Vacuum Ultra Violet

Butadiene is important as the simplest example of resonance between two conjugated double bonds. The comparison of its ultra-violet absorption spectrum with that of ethylene might be expected to give some indication of the way the π electrons of the molecule are affected by the resonance. The electronic structures of a number of molecules for which resonance is important have been worked out theoretically by Hückel (1935), Lennard- Jones (1937), Sklar (1937) and Mulliken (1939 a and b ). The purpose of the present work is to obtain spectroscopic data with which the theoretical expectations can be compared. As most of the strong absorption bands of these molecules occur at wave-lengths less than 2000 A, the investigation falls naturally into the region of vacuum spectroscopy.

Rydberg series and autoionization resonances in the Y I absorption spectrum

1973 ◽  
Vol 333 (1592) ◽  
pp. 17-24 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Ionization Potential ◽  
Excited States ◽  
Spectral Range ◽  
Ground State ◽  
Rydberg Series ◽  
A Value ◽  
Doublet Ground State ◽  
Ionization Limit ◽  
First Ionization Potential

The absorption spectrum of yttrium vapour has been photographed in the spectral range 1650 to 2250 À, with a 10 m spectrograph. Series of autoionization resonances, which converge on excited states of the Y + ion have been identified, as combinations with the doublet ground-state of Y I , 5s 2 4d 2 D 3/2 , 5/2 . Although the lines of these series show broadened and often asymmetrical profiles, the lines are sufficiently well defined to fix a value for the first ionization potential of Y I , which differs from the previously accepted value by approximately 2500 cm -1 . In addition, approximately 400 new Y I lines, which involve excited levels below the first ionization limit of Y I , namely 4s 2 1 S o , have been found. The majority of these are unclassifiable at present but, the value for the first ionization-potential being known from the resonances above-mentioned, two series of the character 5s 2 4d 2 D 3/2 , 5/2 -5s 2 nf 2 F o have been identified. In addition to the identifications of series, 152 new lines below the 5s 2 1 S o limit identify 76 new levels of Y I , of odd parity.

scholarly journals The absorption spectrum of formic acid in the vacuum ultra-violet

1937 ◽  
Vol 162 (908) ◽  
pp. 110-120 ◽  
Keyword(s):  
Electronic Structure ◽  
Formic Acid ◽  
Absorption Spectra ◽  
Ultra Violet ◽  
The Body ◽  
Hydrogen Atoms ◽  
Absorption Bands ◽  
Additional Absorption ◽  
Lyman Continuum ◽  
Vacuum Ultra Violet

Absorption spectra in the far ultra-violet region of the spectrum have recently assumed an important role in fixing the electronic structures of polyatomic molecules. This has been especially true of organic molecules such as acetylene, ethylene, the alkyl halides, alcohols, ethers and ketones. While all “molecular electrons” (i. e. those not contained in inner shells) can be expected to give rise to absorption bands in the region 2000–1000 A, it most frequently happens that one special electron type dominates the absorption. For example, the excitation of non-bonding pπ electrons dominate the absorption of methyl and ethyl iodides (Price 1936 a ); so-called “lone pairs” located on the oxygen atoms are responsible for all the strong bands of water, formaldehyde, etc. (Mulliken 1935 a, b ; Price 1935 a , 1936 b ). In order to obtain discrete absorption bands, which are desirable for the purposes of interpreting electronic structure, it is usually necessary to take the very simplest organic molecule containing the group we wish to study. Thus for molecules of the type R 1 COO R 2 ( R being an alkyl group or a hydrogen atom) it has been found that only the simplest of these, namely formic acid, shows discrete absorption bands. The interpretation of the electronic structure of the carboxyl group will therefore depend to a considerable extent upon the analysis of these discrete bands. From the discussion which follows it will be easy to see why the continuous absorption from the larger molecules of the type R 1 COO R 2 follows roughly the envelope of the discrete absorption of HCOOH except in so far as it is enhanced in certain regions by additional absorption from C—C and C—H bonding electrons or suffers small shifts to longer wave-lengths as a result of the substitution of hydrogen atoms by alkyl groups. The experimental technique employed in obtaining absorption spectra in the vacuum ultra-violet has been described elsewhere (Collins and Price 1934). The Lyman continuum serves as the background against which the 19340. The Lyman continuum serves as the background against which the absorption is observed, and the gas under investigation is allowed to flow continuously through the body of the spectrograph.

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