The Absorption Spectra of Benzoic Acid and Esters

Ungnade, Herbert E.; Lamb, Robert W.

doi:10.1021/ja01135a022

Cited by 37 publications

(16 citation statements)

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“…The absorption spectra of p-TPh and p-QPh in chloroform show maxima in accord with data given in the literature (44,61,62). These maxima allow us to calculate the excitation energies AE' related to isolated molecules; they are 4.…”

Section: Mark and Helfrichsupporting

confidence: 89%

Thermal Activation Energy and Semiconducting Properties of Macromolecular Substances

Szymański

Κryszewski

1969

J. polym. sci., C Polym. symp.

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SynopsisIn many cases the values of thermal activation energy E , identified with half of the energy gap E, are given for characterization of semiconducting properties of polymers. This is justified only in the case of intrinsically generated current carriers and leads to some misunderstanding when the creation of carriers is more complicated, as when they can be injected from the electrodes. The defects of structure act as carrier traps changing the mechanism of conductivity. To investigate the influence of structure on E , values the dependence of current on temperature, current-voltage characteristics, and thermally stimulated currents (TSC) in poly(p-phenyl) oligomers, i.e. p-terphenyl (p-TPh) and p-quaterphenyl (p-QPh), and in poly(p-phenyl) (p-PPh), were studied. The p-TPh and p-QPh in the form of monocrystals and vacuum-deposited layers were investigated; p-PPh, in the form of tablets obtained from mixtures of it and p-TPh and polystyrene. On the basis of current-voltage characteristics the trap density N T were calculated. The measurements of TSC allow estimation of the energy E T of trap levels. From the relation I = f(l/T), where I is current and T is temperature, the E, values for equilibrium conditions were calculated. The mathematical analysis of the trapping and thermal-release phenomena of current carriers shows that the relation log D = f (UT) gives only the average E value, which depends strongly on trap depths and trap population; thus E, has only a limited meaning for the characterization of the organic semiconductor.The semiconducting properties of macromolecular substances are usually characterized by the thermal activation energy E , and the specific resistance p . Since specific resistance depends on many factors, more importance is given to the E , value, which in many cases is identified with half of the energy gap E, between the conduction and valence bands. This interpretation is justified when current carriers are intrinsically generated and thermally activated from the valence band to conducting band.The physical meaning of E, has been discussed in many monographs devoted to low and high molecular weight organic semiconductors (1-5) 867

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Section: Mark and Helfrichsupporting

confidence: 89%

Thermal Activation Energy and Semiconducting Properties of Macromolecular Substances

Szymański

Κryszewski

1969

J. polym. sci., C Polym. symp.

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“…23 The absorption peak of HfBA nanoparticles is slightly shifted to 285 nm, consistent with the C-band position of benzoic acid. 24 Nevertheless all three hybrid nanoparticles showed significant and similar UV absorption at 254 nm, the wavelength of the UV lamp source used in the follow up experiments.…”

Section: Methodsmentioning

confidence: 88%

Studying the Mechanism of Hybrid Nanoparticle Photoresists: Effect of Particle Size on Photopatterning

Chakrabarty

Spyrou

et al. 2015

Chem. Mater.

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Hf-based hybrid photoresist materials with three different organic ligands were prepared by a sol-gel based method and their patterning mechanism was investigated in detail. All hybrid nanoparticle resists are patternable using UV exposure. Their particle sizes show a dramatic increase from the initial 3-4 nm to sub-micron size after exposure, with no apparent inorganic content or thermal properties change detected. XPS results showed that the mass percentage of the carboxylic group in the structure of nanoparticles decreased with increasing exposure duration. The particle coarsening sensitivities of those hybrid nanoparticles are consistent with their EUV performance. The current work provides an understanding for the development mechanism and future guidance for the design and processing of high performance resist materials for large-scale microelectronics device fabrication.

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“…Based on the currently available data on the structure of melanoidins, their spectra in the first approximation should be the additive sum of the absorptions of many chromophore systems. The bands at 205 and 270 nm were B-band and C-band caused by A 1g ’→B 1u ’ and A 1g ’→B 2u ’ transitions, respectively [ 73 ], and the redshift of the spectrum compared to that of benzene was due to the influence of substituents, such as hydroxyls, alkyls, etc. [ 74 ].…”

Section: Resultsmentioning

confidence: 99%

Water-Soluble Melanoidin Pigment as a New Antioxidant Component of Fermented Willowherb Leaves (Epilobium angustifolium)

2021

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Willowherb (Epilobium angustifolium L., family Onagraceae) is a well-known food and medicinal plant used after fermentation as a source of beverages with high antioxidant potential. Despite this long history of use, only a few papers have described the chemical profile and bioactivity of fermented willowherb tea in general. To understand the basic metabolic differences of non-fermented and fermented E. angustifolium leaves, we used general chemical analysis, high-performance liquid chromatography with photodiode array detection and electrospray ionization triple quadrupole mass spectrometric detection assay, and an isolation technique. As a result, the content of 14 chemical groups of compounds was compared in the two plant materials; 59 compounds were detected, including 36 new metabolites; and a new water-soluble phenolic polymer of melanoidin nature was isolated and characterized. The fundamental chemical shifts in fermented E. angustifolium leaves relate mainly to the decrease of ellagitannin content, while there is an increase of melanoidin percentage and saving of the antioxidant potential, despite the significant changes detected. The strong antioxidative properties of the new melanoidin were revealed in a series of in vitro bioassays, and a simulated gastrointestinal and colonic digestion model demonstrated the stability of melanoidin and its antioxidant activity. Finally, we concluded that the new melanoidin is a basic antioxidant of the fermented leaves of E. angustifolium, and it can be recommended for additional study as a promising food and medicinal antioxidant agent.

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The Absorption Spectra of Benzoic Acid and Esters

Cited by 37 publications

References 0 publications

Thermal Activation Energy and Semiconducting Properties of Macromolecular Substances

Thermal Activation Energy and Semiconducting Properties of Macromolecular Substances

Studying the Mechanism of Hybrid Nanoparticle Photoresists: Effect of Particle Size on Photopatterning

Water-Soluble Melanoidin Pigment as a New Antioxidant Component of Fermented Willowherb Leaves (Epilobium angustifolium)

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