High-intensity absorptions

Absorption with e > 104 is considered high-intensity absorption. 

The high intensity absorption of the species BH+C1 indicates the presence of a system of conjugated double bonds. With increasing acidity of the solvent, the absorption due to BH+C1 diminishes and disappears... 

Figure 2. Schematic representation of some relevant ground and excited-state properties of Ru(bpy)j. MLCT and MLCT are the spin-allowed and spin-forbidden metal-to-ligand charge transfer excited states, responsible for the high intensity absorption band with = 450 nm and the luminescence band with = 615 nm, respectively. The other quantities shown are intersystem crossing efficiency energy (E°°) and lifetime (x) of the MLCT state luminescence quantum yield ( ) quantum yield for ligand detachment (O,). The reduction potentials of couples involving the ground and the MLCT excited states are also indicated.

Chalcogenometalate ions are distinguished by characteristic high-intensity absorption bands in the UV-vis region but they can also be traced by IR and Raman spectroscopy. Total assignments and normal coordinate analyses are available for many of the species (also with recourse to isotope shifts, as in the case of MoOjSj-, 92/100MoOS2 or 92,100MoS4-). 

The amount of p,p -dihydroxystilbene structures in kraft lignin was estimated at 0.005 per C6-C3 by oxidation with H202 in the presence of Cu+2 (4) to the stilbenequinone structure (X) which has a high intensity absorption maximum at 478 m/x with c = 40300. 

A third area of high-intensity absorption appears at 250-300 nm for Ph(C C)ioPh, and presumably corresponds to the bands observed in this region for r-Bu(C=C)ioBu-t... 

Nitroalkenes (nitroolefins) are marked by the conjugation of double bonds with those of the nitro group. They show a high intensity absorption band due to JT —transition within the range 220-250 nm. The n — tt band is strongly overlapped there by the intense red shifted absorption band. The... 

Both evidence of the browning caused by the high-intensity absorption of conjugated chromophoric groups and upward shifts in the ultraviolet-visible spectral baselines indicate that higher hydroquinone concentrations produce more polymers. Free radical coupling is probably involved in the polymerization since the existence of free radicals is correlated to hydroquinone concentration. The ultraviolet-visible absorption profiles of these polymers formed in the systems that are not sterilized (Kung and McBride, 1988) appear to be similar to those of phenol-derived polymers in the systems free... 

Aliphatic compounds containing the phenyl derivatives absorb in the 300-325 mp region. 

Mayneord and Roe32 have studied the absorption spectra of several angular condensed ring hydrocarbons. The absorption spectra of these compounds are more complex than those of the members of the linear series. Many of the compounds of the angular series have carcinogenic action and they can be detected in minute quantities spectrophotometrically by virtue of their high intensity absorption bands. 

The term log (/q/T) is also known as the absorbance (or the optical density in older literature) and may be represented by A. The molar absorptivity (formerly known as the molar extinction coefficient) is a property of the molecule undergoing an electronic transition and is not a function of the variable parameters involved in preparing a solution. The size of the absorbing system and the probability that the electronic transition whl take place control the absorptivity, which ranges from 0 to 10 . Values above 10" are termed high-intensity absorptions, while values below 10 are low-intensity absorptions. Forbidden transitions (see Section 7.1) have absorptivities in the range from 0 to 1000. 

The IR spectrum for low density PE in Figure 16.5 shows four high intensity absorption bands. The first band (A) corresponds to the symmetric and asymmetric stretchings of methyl and methylene groups. Then, symmetrical bending of methyl (B) and methylene (C) groups of the polymer... 

The molar absorptivity is a characteristic property of a compound and is not affected by its concentration or the length of the light path. Values range from zero to 10 M cm. Values above 10 M em correspond to high-intensity absorptions values below 10 to low-intensity absorptions. The molar absorptivity... 

Conjugation of the hydroxyimino group with a CC double bond results in the appearance of a highly intense absorption near 236-260 nm (e = 1.1-2.6 X 10 ), probably assignable to rm transitions. 

High-intensity absorption bands of lanthanide (111) vapors and vapor complexes... 

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