Absorption Spectra Of Aqueous Solutions Research Articles

Triplet State of the Nitrite Molecule–Ion

The absorption spectra of aqueous solutions of a number of nitrite complexes exhibit a common absorption band at ∼ 23 kK. This absorption band is responsible for the color of those metal nitrites in which the cation is colorless. This band is assigned as the T1 ← S0 transition of the nitrite molecule–ion. The intensification of the T1 ← S0 transition in the heavier-metal nitrites is a spin–orbit enhancement brought about by the heavy-metal cation. Equilibrium constants for Cd(II), Pb(II), and Tl(I) nitrite complexes- and extinction coefficients for the 23-kK band have been elicited. The 23-kK band is the reverse absorption to the phosphorescence emission; the T1 → S0 radiative lifetimes correlate with those calculated from oscillator strengths of the 23-kK absorption band.

Fundamental vibration frequencies of the main isotopic PO 43− ions in aqueous solutions

The Raman and i.r. absorption spectra of aqueous solutions of normal and 89 atom per cent potassium phosphate, respectively, were compared. The labeled phosphate solution showed the in-phase PO stretching fundamentalsof the P 18 O 4 3− and P 16 O 18 O 3 3− ions at 947±2 and 1035±cm −, respectively, as compared with the 937±2 cm − frequency observed for the corresponding P P 16O 4 3− vibration. The out-of-phase PO stretching band of the aqueous P 18O 4 3− ion appears also at a higher frequency (∼ 1050 cm −1) than the corresponding P 16O 4 3− band ( ca. 1012 cm −1). The observed increase in the PO stretching frequencies of the 18O-labeled ions seems to be the result of an appreciable decrease in the hydrogen bonding of the PO 4 3− ions to the aqueous solvent molecules in the case of the 18O-species.

Far-Infrared Absorption Spectra of Aqueous Solutions of Strong Electrolytes

The infrared absorption of solutions of LiCl, KF, KCl, KBr, KI, NaCl, NaBr, NaI, NaNO3, NaClO3, DCl, and NaOD in NaClO4 has been studied in the spectral region 75 to 650 D2O; the absorption of HCl and NaOH solutions in H2O in the region 75 to 1000 cm−1 has also been investigated. Even for the highest concentrations, the solution spectra have a striking resemblance to the spectrum of the solvent. A broad, intense band attributable to the hindered rotation of water molecules and a much less intense band attributable to the hindered translation of water molecules appear in the spectrum of each solution. The frequencies, widths, and shapes of these bands are compared in some detail with the corresponding bands in the spectrum of pure water. Small but significant differences between the spectra of the solutions and the spectrum of water are noted.

The electronic absorption spectra and the electronic structures of cytosine, isocytosine, and their anions and cations

The electronic absorption spectra of cytosine and isocytosine have been measured in several solvents at room temperature, and the temperature and pH dependencies of the electronic absorption spectra in aqueous solution have also been examined, special attention being paid to the existence of tautomeric forms. Consequently, it is concluded that cytosine in aqueous solution takes 2-keto-6-amino (3H) form (I) at room temperature, but with rising temperature 2-keto-6-imino form (III) coexists with form I, the latter being determined to be more stable by 5.5 kcal/mole than the former, and that cytosine takes form I and form III in trimethyl phosphate and in acetonitrile, respectively. The change in stability of the tautomeric forms by different solvents has been discussed with regard to their calculated dipole moments due toπ-electrons and the polarity of the solvents.

Electronic absorption spectra of metallic azides, perchlorates and nitrates and their related explosive properties

Electronic absorption spectra of aqueous solutions of Na, K, Ba, Ag and Pb azides, perchlorates and nitrates have been measured. For a particular series it has been found that these spectra are unique and the observed absorption has been attributed to excitations from the highest occupied molecular orbital to the lowest unoccupied molecular orbital. Spectra of single crystals of all these salts have also been measured. It is found that those salts which absorb on the long wavelength side of the anionic absorption are the heavy metal salts, specifically the elements not having closed shell configurations. In each of these three series it is these same salts which are the most unstable, e.g. Pb(N 3) 2 is much more unstable than NaN 3. There is therefore a direct correlation between the absorption spectra of these materials and their sensitivity.

Systematic Synthesis of Ammine Series of Chromium(III) Complexes

Abstract The systematic synthesis of ammine series of chromium (III) complexes has been developed by using aquopentamminechromium(III) nitrate as a starting material. The procedure for the preparation of aquopentamminechromium(III) nitrate was improved to increase the yield. Twenty five sorts of chromium(III) complexes were obtained by the systematic synthesis, of which the procedures for the preparation of eleven sorts of complexes including a new complex, dinitritotetramminechromium(III) bromide, are described. The visible and ultraviolet absorption spectra in aqueous solutions and infrared spectra in solid state of those complexes have been obtained and their structures are discussed.

Comparative Interpretation of Absorption Spectra of Technetium (IV) and Rhenium (IV) Hexahalides

Absorption spectra of aqueous solutions of TcX6 - and ReX6 - (X = F, Cl, Br, I) are measured between 8 000 and ∼ 50 000 cm-1 and theoretically discussed. The electron transfer spectra indicate the optical electronegativity xopt= 2.25 for Tc (IV) and 2.05 for the less oxidizing Re (IV). The spectrochemical parameter Δ is determined to 28 400 cm-1 in TcF6 and 32 800 cm-1 in ReF6 -. The nephelauxetic effect is evaluated from the spin-forbidden intra-sub-shell transitions in all eight species, and from the two spin-allowed bands of TcF6 - The vibrational structure of the narrow absorption bands and the possible weak distortion from octahedral symmetry of Tc (IV) hexahalides are discussed.

Infrared Attenuated Total Reflection Spectra of Aqueous Solutions of Some Amino Acids

The technique of total reflection proposed by Harrick (1) using total internal reflection and by Fahrenfort using a single reflection (2) (attenuated total reflection, ATR) seems to hold great promise as opposed to conventional reflection techniques, for the structural and analytical investigations of difficult samples in the infrared region of the spectrum (3,4). Because of the intense absorption by water, the examination of infrared absorption spectra of aqueous solutions requires the use of very thin sample cells with reference beam attenuation or of carefully matched sample and reference cells. It was decided to investigate the possibility of obtaining the infrared ATR spectra of aqueous solutions of some amino acids using the single-reflection ATR accessory available from Barnes Engineering Co., Stamford, Conn. with a prism of AgCl as the reflecting material; the spectra were obtained on a Perkin Elmer model 421 double-beam, infrared spectro-photometer. The angle of reflection was 45°; the slit program was set at 1000, the gain at 5, and source current 0.35 amp. The amino acids used were from commercially available sources.

Absorption spectra of solutions of cyanuric acid and its chlorinated derivatives

The pH dependence of the ultraviolet absorption spectra of aqueous solutions of cyanuric acid and its chlorinated derivatives is attributed to dissociation leading to four species containing the cyanuric nucleus with net charge 0, 1−, 2−, and 3−. Chlorination of cyanuric acid results in more diffuse spectra because several species of a given net charge may exist. At pH 14 the spectra of these solutions are essentially identical regardless of degree of chlorination and the principal organic ion present presumably is the triply charged cyanurate. The value of p K 3 of cyanuric acid is estimated from spectral changes to be about 13. The assignments of electronic transitions and molecular structure are discussed.

Absorption Spectra in Irradiated Water and Some Solutions: Absorption Spectra of ‘Hydrated’ Electron

The absorption spectra of aqueous solutions after exposure to a pulse of 1.8 Mev electrons reveal a broad transient absorption band that is believed to be due to the hydrated electron, the existence and properties of which are predicted by Platzman. Aqueous ammonia solutions of various concentrations are exposed to 1.8 Mev electrons and their absorption spectra observed. The transient spectrum observed is assumed to be due to an electron trapped in the water. (D.C.W.)

Spectroscopic studies on rare-earth compounds—II

The absorption spectra of aqueous solutions of neodymium perchlorate between 4000 Å and 9000 Å have been measured at 3° using a spectral bandwidth of 1 Å. Several new bands and inflections are reported. A rather pronounced similarity was found between these spectra and the spectrum of crystalline neodymium bromate-enneahydrate. The absorbancy indexes of the principal absorption maxima of aqueous solutions of neodymium perchlorate were found to depend linearity on the reciprocal of the absolute temperature in the range between 3 and 60°.

Alizarin sulphonate complexes of zirconium and hafnium

The reaction of alizarin S with dilute (10 −4 M) zirconium and hafnium solutions in 0·1 M HClO 4 was studied amperometrically. An insoluble compound formed initially but redissolved upon the addition of excess metal ion. The stoichiometry for these two species depended upon the age of the metal ion solution. The mole ratio of zirconium to alizarin S at the first end point increased from 0·8 to 1·0 as the solution aged and for hafnium from 0·81 to 0·88 over the same period. For the second end point, the ratio ranged from 1·2 to 1·75 for zirconium and remained constant at 1· for the hafnium solutions. The ultra-violet and visible absorption spectra of aqueous solutions of these two compounds were the same. From the amperometric and spectral data it was concluded that the metal was chelated by a quinoid oxygen and the alpha phenolic oxygen. Solubilization of the initial precipitate probably involves the reaction of additional metal ions with the chelated metal.

On the Base Strength of Some Nitrogen Heterocycles in the Excited State

Abstract 1. The fluorescence and absorption spectra of aqueous solutions of quinoline, acridine and 2,8-diaminoacridine were observed at various pH values, and it became clear that the stabilization energy by proton addition is larger in the excited state than in the ground state. 2. The effects of hydrogen bonding and proton addition upon the spectra were confirmed to be the same in tendency. 3. On the basis of the fluorescence intensities in various organic solvents, some discussions were made about the contribution of non-bonding electron to the inner quenching of fluorescence. 4. The vapor spectrum of quinoline was-taken and line spectra were observed, which are most certainly attributable to n→π* transition.

Eine spektrophotometrische Bestimmungsmethode für saure und alkalische Phosphatasen

AbstractA rapid and very sensitive spectrophotometric method for the determination of the acid and alkaline phosphatases is given, using o‐carboxyphenyl‐phosphate as a substrate. This compound has been purified and characterized by its melting point and absorption spectra in aqueous solutions of different pH. Hydrolysis of the ester can be followed continuously by measuring the increase of extinction at 298 mm̈.

The absorption of light in solutions of the rare earth salts

For completion the series of previous publications on rare earths spectra the absorption spectra of aqueous solutions of europium, terbium and erbium salts are reported. A list of the oscillator strengths of all rare earths is given and the results are shown in a diagram.

The absorption of light in aqueous solutions of dysprosium, holmium and thulium salts

Summary The absorption spectra of aqueous solutions of Dy, Ho and Tm salts have been measured, and the absolute intensities of the bands and the absorption probabilities are given.

The absorption of light by neodymium salts in the near ultra-violet region

Summary The absorption spectra of aqueous solutions of NdCl 3 and Nd(NO 3 ) 3 communicated in 1), are measured again in the near ultra-violet region, and corrected values are given.

The light absorption in the near infra red region of praseodymium, samarium and ytterbium solutions

The absorption spectra of aqueous solutions of Pr, Sm and Yb chlorides and nitrates, and the absolute intensities of the absorption bands in the near infra-red region (from 11000 down to 7000 Å) are determined by a photoelectric method.

The absorption of light in aqueous solutions of neodymium salts

The absorption spectra of aqueous solutions of Nd-salts (chloride and nitrate) and the absolute intensities of the absorption bands from 11000 down to 2900 Å are determined by a photoelectric method. From the results the probabilities of absorption are calculated.

The absorption of light in aqueous solutions of neodymium salts

The absorption spectra of aqueous solutions of Nd-salts (chloride and nitrate) and the absolute intensities of the absorption bands from 11000 down to 2900 Å are determined by a photoelectric method. From the results the probabilities of absorption are calculated.