The spectrum and structure of singlet CH
            2

The red absorption bands of CH 2 , previously shown to correspond to a transition between singlet states, have been analysed in detail. In the lower electronic state a 1 A 1 the molecule is a strongly asymmetric top with rotational constants A 000 = 20.14, B 000 = 11.16 and C 000 = 7.06 cm -1 . From these constants a CH distance of 1.11 A and an HCH angle of 102.4° is obtained. In the upper state b 1 B 1 the molecule is nearly linear, having an HCH angle of about 140° and a CH distance of 1.05 A. Most of the observed absorption bands correspond to excitation of the bending vibration v 2 in the upper state (v 2 = 6, 8, ..., 18). In some of them in addition the symmetric stretching vibration v 2 is singly excited. The levels 1, v 2 -4, 0 cause strong perturbations in the levels 0, v 2 , 0 for v 2 = 8, 10, 12, 14. In the lower state only one excited vibrational level 0, 1, 0 has been established which yields v 2 = 1352.6 cm -1. Fragments of some other singlet absorptions in the near ultraviolet and in the vacuum ultraviolet have been observed and are briefly described. The upper state of the near ultraviolet system is probably the predicted 1 A 1 state corresponding to 1 E + in the linear conformation.

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The absorption spectrum of the free SiH2 radical

Canadian Journal of Physics ◽

10.1139/p68-608 ◽

1968 ◽

Vol 46 (22) ◽

pp. 2485-2490 ◽

Cited By ~ 145

Author(s):

I. Dubois

Keyword(s):

Absorption Spectrum ◽

Electronic State ◽

Vibrational Level ◽

Visible Region ◽

Rotational Structure ◽

Lower State ◽

High Dispersion ◽

Bending Vibration ◽

Lower Electronic State

The absorption spectrum of SiH2 in the visible region has been photographed at high dispersion and the rotational structure of three bands has been analyzed. In the lower electronic state 1A1 the HSiH angle is 92° 5′ and the Si–H distance 1.516 Å, while in the upper state these parameters are 123° and 1.487 Å, respectively. The observed bands correspond to excitation of the bending vibration [Formula: see text] in the upper state. In the lower state, only one excited vibrational level, 010, has been observed, yielding [Formula: see text].

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FTIR STUDY ON MOLECULAR CONTAMINATION ON SURFACE OF OPTICAL MATERIALS

International Journal of Modern Physics B ◽

10.1142/s0217979206040490 ◽

2006 ◽

Vol 20 (25n27) ◽

pp. 3860-3865 ◽

Cited By ~ 1

Author(s):

MASAHIRO KATOH ◽

NOBUAKI OKANO ◽

TOSHIHIDE HORIKAWA ◽

TAHEI TOMIDA ◽

NOBUNARI ITOH

Keyword(s):

Ir Spectra ◽

Optical Materials ◽

Functional Group ◽

The Other ◽

Absorption Bands ◽

Bending Vibration ◽

Absorption Intensity ◽

Stretching Vibration ◽

Optical Disks ◽

Molecular Contaminants

The IR spectra of the molecular contaminants on surface of optical materials were measured. The optical disks used were SiO 2, BK7 ( SiO 2 70%, B 2 O 3 10%, K 2 O 8%, N 2 O 8%), CaF 2, ZnSe and Al 2 O 3. N 2, O 2, H 2 O , and CO 2 were adopted as contamination gases. IR spectra of H 2 O (2.7kPa) on BK7 at 373K showed two absorption bands ( OH stretching vibration: around 4000cm-1-3500cm-1 and OH bending vibration: around 2000cm-1-1500cm-1). The absorption intensity decreased with a decrease in temperature and a new band (around 3250cm-1) appeared at 173K. The new band was attributed to phase transition of H 2 O . These phenomena were also observed on the other three discs, except for SiO 2. IR spectra of SiO 2 showed OH stretching band (3676cm-1). The absorption intensity decreased with a decrease in temperature. But two new bands (3720cm-1 and 3620cm-1) appeared under an atmosphere of N 2 (66.5kPa), O 2 (66.5kPa), H 2 O (2.7kPa) or CO 2 (0.7 or 13.3kPa). A similar phenomenon was also observed for BK7, which has OH group. These results suggested the functional group of SiOH interacted with contamination molecules.

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The near-ultraviolet absorption spectrum of diimide: a re-examination

Canadian Journal of Chemistry ◽

10.1139/v78-255 ◽

1978 ◽

Vol 56 (11) ◽

pp. 1575-1578 ◽

Cited By ~ 21

Author(s):

R. A. Back ◽

C. Willis ◽

D. A. Ramsay

Keyword(s):

Absorption Spectrum ◽

Absorption Spectra ◽

Torsional Vibration ◽

Ultraviolet Absorption Spectrum ◽

Bending Vibration ◽

Vibrational Assignments ◽

Near Ultraviolet ◽

Stretching Vibration ◽

Condon Factors ◽

Franck Condon

The absorption spectra of N2H2 and N2D2 in the region 3000–4300 Å have been re-examined with somewhat higher resolution than was used in earlier work. The vibrational assignments of the principal progressions are unchanged except for the revision of the vibrational numbering suggested by the calculations of Perić, Buenker, and Peyerimhoff in 1977. The transition is electronically forbidden (1Bg–1Ag) but is made vibronically allowed by excitation of one quantum of the antisymmetric stretching vibration ν4′(bu). Weaker progressions are induced by the torsional vibration ν4′(au) and the antisymmetric H—N—N bending vibration ν6′(bu). Agreement between experiment and theory is generally satisfactory though some significant discrepancies in Franck–Condon factors have been noted.

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The absorption spectrum of the free NCO radical

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1960.0003 ◽

1960 ◽

Vol 252 (1007) ◽

pp. 165-192 ◽

Cited By ~ 139

Keyword(s):

Flash Photolysis ◽

Ultra Violet ◽

Fermi Resonance ◽

Spin Splitting ◽

Lower State ◽

State Transitions ◽

Absorption Bands ◽

Bending Vibration ◽

Rotational Constants ◽

Coupling Case

Two systems of absorption bands have been observed in the visible and ultra-violet regions of the spectrum during the flash photolysis of several organic cyanates, and have been photographed under high resolution with long absorbing paths. Extensive vibrational and rotational analyses have been carried out for the bands of one system and show that the spectrum is due to an electronic transition A ( 2 Z + ) <-- X ( 2 II < i ) of the free NCO radical, which is linear in both states. All three vibrational frequencies and the first-order anharmonic constants have been obtained for the upper state, A ( 2 { + ), and give a close fit to the term values of 21 observed vibrational levels. A Fermi resonance has been observed between v ' 1 and 2v' 2 . In addition, the rotational constants B' and D' and their variations with all three fundamental vibrations have been obtained for this state. Transitions have been observed from four excited levels of the bending vibration in the lower state, X ( 2 II i ), and the rotational constants have been determined for some of these levels. Interaction between the electronic and vibrational motions (Renner effect) complicates the vibrational structure of this state. The state belongs to Hund’s coupling case ( a ), and the spin-orbit coupling gives a splitting A" = —95.6 cm<super>-1</super>. In a 2 { + vibronic level of this state (arising from l = 1 and A = 1) the spin sp litting is proportional to N +1/2, but the spin-splitting constant y is unusually large, and amounts to 30 % of the B value. The electronic states of NCO are correlated with those of its dissociation products. This shows that the bond dissociation energy of the CO bond is slightly greater than that of the CN bond in the three known states.

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Graphene Oxide Layer-by-Layer Films for Sensors and Devices

Nanomaterials ◽

10.3390/nano11061556 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1556

Author(s):

Ivan C. C. Assunção ◽

Susana Sério ◽

Quirina Ferreira ◽

Nykola C. Jones ◽

Søren V. Hoffmann ◽

...

Keyword(s):

Graphene Oxide ◽

Electrical Properties ◽

Vacuum Ultraviolet ◽

Morphological Characterization ◽

Linear Increase ◽

Layer By Layer ◽

Absorption Bands ◽

Semiconductor Behavior ◽

Vacuum Ultraviolet Spectroscopy

Layer-by-layer films of poly (allylamine hydrochloride) (PAH) and graphene oxide (GO) were characterized, looking at growth with the number of bilayers, morphology, and electrical properties. The PAH/GO films revealed a linear increase in absorbance with the increase in the number of deposited bilayers, allowing the determination that 10.7 ± 0.1 mg m−2 of GO is adsorbed per unit of area of each bilayer. GO absorption bands at 146, 210, 247 and 299 nm, assigned to π-π* and n-π* transitions in the aromatic ring (phenol) and of the carboxylic group, respectively, were characterized by vacuum ultraviolet spectroscopy. The morphological characterization of these films demonstrated that they are not completely uniform, with a bilayer thickness of 10.5 ± 0.7 nm. This study also revealed that the films are composed of GO and/or PAH/GO fibers and that GO is completely adsorbed on top of PAH. The electrical properties of the films reveal that PAH/GO films present a semiconductor behavior. In addition, a slight decrease in conduction was observed when films were prepared in the presence of visible light, likely due to the presence of oxygen and moisture that contributes to the damage of GO molecules.

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Comparing the Efficiencies of the Removal of Cadmium from Industrial Wastewater Using Zeolites

International Research Journal of Pure and Applied Chemistry ◽

10.9734/irjpac/2020/v21i530166 ◽

2020 ◽

pp. 6-18

Author(s):

Michael Akrofi Anang ◽

Ruphino Zugle ◽

Baah Sefa- Ntiri

Keyword(s):

Rice Husk ◽

Industrial Wastewater ◽

Raw Materials ◽

Research Work ◽

Corn Stalk ◽

Zeolite X ◽

Bending Vibration ◽

Strong Peak ◽

Corn Husk ◽

Stretching Vibration

The presence of heavy metals in industrial wastewater needed to be removed in other to control pollution which has been caused as a result of human and industrial activities. Several adsorbents have been used for the remediation process but with this particular research work, Zeolites were used. They were synthesized hydrothermally from various locally available raw materials namely rice husk, corn stalk, corn husk, and kaolin. They were characterized using their FTIR to determine the functional groups on the material synthesized and also their adsorptive activities were compared with industrially synthesized Zeolite X. A very strong peak at 1052 cm-1 is as a result of the asymmetric vibrations of the internal T-O tetrahedron with a weak symmetric T-O stretching vibration recorded at 797 cm-1. Another strong peak was observed at 445 cm-1 as a result of the O-T-O bending vibration which confirms the presence of a five-membered structure. The adsorptive properties of the synthesized Zeolites were evaluated by using them to remove Cadmium ions from solution and their percentage removals were determined. Similarly, their adsorption kinetics were also determined and was observed the R2 values to be 0.9093 and 0.9454 for Corn husk and Cornstalk for the first order and the second order with R2 values of 1 for rice husk, kaolin and corn stalk.

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Infrared Absorption Spectra of Vinyl Esters of Carboxylic Acids

Applied Spectroscopy ◽

10.1366/000370270774372489 ◽

1970 ◽

Vol 24 (5) ◽

pp. 495-498 ◽

Cited By ~ 9

Author(s):

George E. McManis

Keyword(s):

Vinyl Ester ◽

Ester Group ◽

Vinyl Esters ◽

Deformation Bands ◽

Absorption Bands ◽

Esters Of Carboxylic Acids ◽

Sharp Band ◽

Out Of Plane ◽

Stretching Vibration ◽

Infrared Absorption Spectra

The ir spectra of compounds containing the vinyl ester group exhibit absorption bands that allow them to be readily distinguished from other monosubstituted ethylenic compounds and from other esters. The vinyl C=C stretching vibration is a strong sharp band at 1640 cm−1, which is quite useful in analytical procedures. The C–H stretching vibrations of the vinyl ester group are observed as two weaker bands at 3117 and 3040 cm−1 flanking a larger sharp band at 3091 cm−1. In-plane C–H deformation bands are noted at 1413, 1291, and 1092 cm−1, while out-of-plane deformations are at 947, 868, and 603 cm−1. The stretching vibration of the ester carbonyl is a strong sharp band at 1754 cm−1. The C–O stretching region is dominated by a very strong band at 1142 cm−1.

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ABSORPTION SPECTRA OF ETHYLENE AND ETHYLENE-d4 IN THE VACUUM ULTRAVIOLET. II

Canadian Journal of Physics ◽

10.1139/p56-073 ◽

1956 ◽

Vol 34 (7) ◽

pp. 643-652 ◽

Cited By ~ 74

Author(s):

P. G. Wilkinson

Keyword(s):

Absorption Spectra ◽

Vacuum Ultraviolet ◽

Stable Equilibrium ◽

Equilibrium Configuration ◽

Rydberg States ◽

Torsional Oscillator ◽

Potential Barriers ◽

First Order ◽

Stretching Vibration ◽

Vibrational Constants

The absorption spectra of ethylene and ethylene-d4 have been investigated in the 1300 Å to 1500 Å region using the first order of a 21-ft. vacuum grating spectrograph. Vibrational constants for the v2(ag) stretching vibration and the v4(au) twisting vibration have been determined for each of the observed five Rydberg states. The torsional oscillator–rotator treatment has been applied to the observed twisting data, and potential barriers hindering free rotation of 500 to 1200 cm−1 were obtained. It is concluded that the stable equilibrium configuration of the Rydberg states is not of D2h symmetry but is probably bent or staggered.

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Micro-FTIR and EPMA Characterisation of Charoite from Murun Massif (Russia)

Journal of Spectroscopy ◽

10.1155/2018/9293637 ◽

2018 ◽

Vol 2018 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Maria Lacalamita

Keyword(s):

Single Crystal ◽

Complex Structure ◽

Structural Complexity ◽

Adsorbed Water ◽

Bending Vibration ◽

Structural Water ◽

Stretching Vibration ◽

Vibrational Features ◽

Polytype Structure ◽

Insight Into

Combined micro-Fourier transform infrared (micro-FTIR) and electron probe microanalyses (EPMA) were performed on a single crystal of charoite from Murun Massif (Russia) in order to get a deeper insight into the vibrational features of crystals with complex structure and chemistry. The micro-FTIR study of a single crystal of charoite was collected in the 6000–400 cm−1 at room temperature and after heating at 100°C. The structural complexity of this mineral is reflected by its infrared spectrum. The analysis revealed a prominent absorption in the OH stretching region as a consequence of band overlapping due to a combination of H2O and OH stretching vibrations. Several overtones of the O-H and Si-O stretching vibration bands were observed at about 4440 and 4080 cm−1 such as absorption possibly due to the organic matter at about 3000–2800 cm−1. No significant change due to the loss of adsorbed water was observed in the spectrum obtained after heating. The occurrence of well-resolved water bending vibration bands at about 1595 and 1667 cm−1 accounts for more than one structural water molecule as expected by charoite-90 polytype structure model from literature. The chemical composition of the studied crystal is close to the literature one.

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