Matrix absorption spectra of the radicals formed by the addition of hydrogen atoms to phenylacetylene

SummaryThe crystal structure of the clay mineral dickite (Al2Si2H4O9) has been refined to a greater accuracy than that reported in an earlier analysis. Improved lattiçe parameters are: a 5·15±0·001, b 8·940±0·001, c 14·424 ± 0·002Å., β 96° 44′± 1′. The dickite structure shows several significant distortions from the geometry of the idealized kaolin layer, including deformation and rotation of the silica tetra-hedra. The most striking features of the octahedral layer are the extremely short shared edges of 2·37 Å. Although the analysis was not sufficiently accurate to position the hydrogen atoms with certainty, a model consistent with the infrared absorption spectra is proposed. The stacking sequences of kaolin-layer minerals have been considered with reference to the structural features observed in dickite. There are thirty-six ways of superposing two kaolin layers commensurate with the OH-O bonds found in kaolinite, dickite, and nacrite. The twelve sequences showing the least amount of cation-cation superposition between consecutive kaolin layers can be used to construct two one-layer cells, kaolinite and its mirror image, and twelve two-layer cells, including dickite and nacrite. The distortions of the kaolin layer introduce secondary variations in the interlayer bonding that suggest that dickite and nacrite are the most stable of the kaolin layer structures, since they possess the shortest oxygen-hydroxyl contacts.

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

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1937.0170 ◽

1937 ◽

Vol 162 (908) ◽

pp. 110-120 ◽

Cited By ~ 21

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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XLVIII.—The absorption spectra of substances containing labile hydrogen atoms

Journal of the Chemical Society Transactions ◽

10.1039/ct9130300406 ◽

1913 ◽

Vol 103 (0) ◽

pp. 406-419

Author(s):

Peter Joseph Brannigan ◽

Alexander Killen Macbeth ◽

Alfred Walter Stewart

Keyword(s):

Absorption Spectra ◽

Labile Hydrogen ◽

Hydrogen Atoms

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Optical Absorption Study of Hydrogen In Zn-Doped Si

MRS Proceedings ◽

10.1557/proc-513-357 ◽

1998 ◽

Vol 513 ◽

Author(s):

M. Suezawa

Keyword(s):

Optical Absorption ◽

Absorption Spectra ◽

Hydrogen Atmosphere ◽

Electronic Transitions ◽

Optical Absorption Spectra ◽

Hydrogen Atoms ◽

Ir Spectrometry ◽

Co Doping ◽

Ft Ir ◽

Hydrogen Bound

ABSTRACTWe studied the interaction between hydrogen (H) and Zn or Zn-related defects in Zn-doped Si crystals from the measurements of optical absorption spectra of hydrogen bound to Zn or Znrelated defects. We doped Si crystals with Zn by annealing the crystals in Zn vapor at 1200°C followed by quenching. After Zn-doping, we doped specimens with H by annealing them in a hydrogen atmosphere followed by quenching. We measured optical absorption spectra of the above specimens at about 6 K by means of FT-IR spectrometry. Many optical absorption peaks were observed; some are due to electronic transitions and some are due to vibrational transitions of H vibration. Hydrogen atoms are known to passivate Zn acceptors since the optical absorption intensity associated with electronic transitions become much weaker after hydrogenation. Absorption peaks associated with H vibration are known to be related to complexes composed of one Zn atom and two hydrogen atoms. We concluded this from studies on the effect of co-doping with H and deuterium and the effect of Zn isotopes on the optical absorption spectra due to H.

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Remarks on the diffuse interstellar lines

Symposium - International Astronomical Union ◽

10.1017/s0074180900100750 ◽

1967 ◽

Vol 31 ◽

pp. 91-93 ◽

Cited By ~ 4

Author(s):

G. Herzberg

Keyword(s):

Hydrogen Atoms ◽

Interstellar Gas

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.

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Ultraviolet Absorption of Refractory Elements by a Dual Laser Plasma Method

International Astronomical Union Colloquium ◽

10.1017/s0252921100107821 ◽

1988 ◽

Vol 102 ◽

pp. 243-246

Author(s):

J.T. Costello ◽

W.G. Lynam ◽

P.K. Carroll

Keyword(s):

Absorption Spectra ◽

Laser Plasma ◽

Optical Pulse ◽

Ionic Species ◽

Neutral Species ◽

Plasma Method ◽

Plasma Technique ◽

Refractory Elements ◽

Delay Times ◽

Dual Laser

AbstractThe dual laser-produced plasma technique for the study of ionic absorption spectra has been developed by the use of two Q-switched ruby lasers to enable independent generation of the absorbing and back-lighting plasmas. Optical pulse handling is used in the coupling cicuits to enable reproducible pulse delays from 250 nsec. to 10 msec, to be achieved. At delay times > 700 nsec. spectra of essentially pure neutral species are observed. The technique is valuable, not only for obtaining the neutral spectra of highly refractory and/or corrosive materials but also for studying behaviour of ionic species as a function of time. Typical spectra are shown in Fig. 1.

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XUV Absorption Spectra of Carbon Ions

International Astronomical Union Colloquium ◽

10.1017/s0252921100107444 ◽

1988 ◽

Vol 102 ◽

pp. 71-73

Author(s):

E. Jannitti ◽

P. Nicolosi ◽

G. Tondello

Keyword(s):

Absorption Spectra ◽

Cross Section ◽

Theoretical Calculations ◽

Photoionization Cross Section ◽

Carbon Ions

AbstractThe photoabsorption spectra of the carbon ions have been obtained by using two laser-produced plasmas. The photoionization cross-section of the CV has been absolutely measured and the value at threshold, σ=(4.7±0.5) × 10−19cm2, as well as its behaviour at higher energies agrees quite well with the theoretical calculations.

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