Absorption Spectrum Of Chlorophyll Research Articles

Absorption spectra of chlorophyll a in aqueous carbitol solvents

The absorption spectrum of chlorophyll a in aqueous methyl and butyl carbitol has been measured. The red-absorption maximum of chlorophyll dissolved in methyl carbitol (665 mμ) shifts to the red as the solvent is made increasingly aqueous (672 mμ in 30% methyl carbitol). Concurrently, the extinction coefficient decreases and fluorescence is lost. It has also been shown that only the non-fluorescent form of chlorophyll can form a colloid absorbing at 685 mμ in the presence of 6% dioxane. Butyl carbitol is more effective than methyl carbitol in keeping chlorophyll in a fluorescent form at high water concentrations, some fluorescence persisting when the solvent is 70–80% aqueous. Dioxane colloids prepared in 10% butyl carbitol exhibit an absorption maximum at 690 mμ, with a subsidiary maximum at 695 mμ. The 695-mμ absorption is considerably strengthened on standing. Thus, in these two solvent systems it is possible to prepare colloidal states of chlorophyll absorbing maximally at 672, 685, 690, and 695 mμ.

Visible absorption spectrum of chlorophyll a, b, and beta-carotene molecules mixed in monolayers at a water-air interface.

IN a previous communication1, visible absorption spectra of chlorophyll a or b in monolayers were compared with those taken in several organic solvents. The red and blue absorption peaks of the chlorophylls in monolayers at water–air and water–oil interfaces were found to be shifted towards longer wavelengths as compared with their solution peaks. This shift was postulated to be possibly due to a physical condensed state of the molecules in monomolecular layers, stressing the possibility that the chlorophylls in green plants in vivo are in films adsorbed at liquid interfaces. The results to be presented here not only confirm the above possibility, but also show that the three major pigments of the lamellar structure of the chloroplast could account for almost all the contribution in absorbance. The incorporation of β-carotene in mixed films of chlorophyll a and b became possible after it was found that β-carotene could be used in films2.

The derivative absorption spectra of chlorophyll in algae and leaves at low temperatures

Chlorophyll a in live plants is found in several spectroscopically distinct combinations which are difficult to recognize because their absorption bands strongly overlap. These spectral bands can be distinguished, however, through derivative spectrophotometry, especially at low temperatures which sharpens the bands and makes possible the detection of smaller amounts of minor components than is possible with measurements at room temperature. The derivative absorption spectra of a number of algae and leaves were measured at room temperature and at about — 180°. For example, at low temperature, in the spectra of Porphyridium cruentum, Phormidium persicinum, and lettuce leaf, a shoulder appeared with maximum probably near 655 mμ which belonged to an unidentified component.

The viscosity of chlorophyll in organic solvents

Chlorophyll was dissolved in various concentrations in organic solvents, and from the rate of flow of solutions in a viscometer, the intrinsic viscosities were measured. The values were found to vary widely according to the solvent used and the concentration of chlorophyll. The values obtained for the intrinsic viscosities under different conditions fell in two separate ranges, 2.5–3.2 and 16–22, indicating that the phytol group in the chlorophyll molecule does not have rigid structure but fluctuates between two configurations according to the conditions. Situations were entirely different in the case of dilute solutions in methanol and α-picoline, in which case the intrinsic viscosity ran up to such an abnormally high level that it could not be accounted for by any possible configuration of single chlorophyll molecules. Also the absorption spectrum of chlorophyll was measured in methanol and α-picoline at various concentrations in an attempt to detect whether the anomalous viscosity is accompanied by a change in the optical property which may have a correlation to the state of the molecule in solution.

The Photoelectric Theory of Photosynthesis. V. Further Correlation of the Absorption Spectrum of Chlorophyll with the Emission Spectrum of Magnesium

The near infrared absorption spectrum of chlorophyll has been reexamined in an attempt to detect a possible weak absorption at around 881 mμ, corresponding to the only important emission line of Mg atoms above 655 mμ, and which is due to the transition 3p → 3d for Mg. Chlorophyll is found to exhibit such a band in the region 860–885 mμ. This is interpreted as further evidence for the author's photoelectric theory of photosynthesis, in which it is postulated that it is the Mg atom of chlorophyll which is electronically excited by light absorption. Seven new bands are predicted for chlorophyll in the far ultraviolet region of the spectrum, ranging from 273 to 123 mμ, and the ionization potential of chlorophyll is calculated to be 189 v.

Chloroplast studies: I. Absorption spectra of chlorophyll monolayers at liquid interfaces

The absorption spectra of chlorophyll a and b monolayers, under known thermodynamic conditions, at water/air and water/oil interfaces, have been compared with absorption spectra of these pigments in several organic solvents. The results strenthen the hypothesis that in living chloroplasts chlorophyll is in a monolayer state.

Spectroscopic properties of crystals and monolayers of chlorophyll and related compounds

Microcrystals of ethyl chlorophyllides and pheophorbides a and b, and of methyl bacteriochlorophyllide, have been prepared and their absorption spectra measured. The main long-wave bands are shifted toward longer waves by 1–2 × 10 3 cm. −1 compared to their (extrapolated) position in free molecules ( i.e., by 40–80 mμ from their position in organic solvents). The shift is a function of the size of the microcrystals, reaching “saturation” in crystals about 0.5 μ in diameter. An only slightly smaller shift is observed in “crystalline” monolayers, indicating that the interactions responsible for the shift occur mainly in one crystallographic plane. In “liquid” monolayers, the shift is much smaller—similar to that in amorphous colloidal solutions. A theory of the band shift is given, based on electrostatic interaction in an isotropic array of (virtual) dipoles, created by light absorption (without consideration of the overlapping of eigenfunctions and consequent resonance effects). The absolute value of the maximum shift in “large” microcrystals, and, in particular, the shape of the curve showing the dependence of the shift on crystal size, support the assumption of a predominantly two-dimensional interaction. The significance of these results for the hypothetical chlorophyll monolayers in vitro and the possible migration of excitation energy in them is discussed. Absence of fluorescence suggests that migration must be very restricted—if at all existent—in crystals and crystalline monolayers; it could be more extensive in noncrystalline monolayers. The existence of monolayers of the latter type is compatible with the absorption spectrum of chlorophyll in vivo.

Localisation of chlorophyll within the chloroplast

Silver nitrate reduction was shown to occur in illuminated suspensions of Hibiscus grana. The action spectrum of this reduction, the Molisch reaction, proved to coincide satisfactorily with the chlorophyll absorption spectrum. Electron micrographs reveal that this reaction occurs in single lamellae. From this it is concluded that lamellae are the bearers of chlorophyll.

Absorption spectra of chlorophylls in solutions at low temperatures; equilibria between isomers.

Absorption spectra of chlorophylls in solutions at low temperatures; equilibria between isomers.

The Absorption Spectra of Chlorophyll and Related Compounds.

The Absorption Spectra of Chlorophyll and Related Compounds.

Self-Quenching and Sensitization of Fluorescence of Chlorophyll Solutions

The intensity of fluorescence of solutions of chlorophyll (either a or b) is sensibly independent of concentration, for values less than 2×10−3m. At higher concentrations, the fluorescence decreases with increasing concentration, conforming to the empirical equation, If,max/If=1+4300m2. The absorption spectrum of chlorophyll a is the same at 0.02m as it is for very dilute solutions. These results, as well as the observed temperature coefficient of the fluorescent intensity, indicate that the self-quenching of chlorophyll solutions is not due to the formation of non-fluorescent dimers nor to collisions of the second kind, but is very probably related to the resonance exchange of excitation (16, 17) between an excited and normal chlorophyll molecule. Measurements of the fluorescence intensity of solutions containing mixtures of chlorophylls a and b indicate that chlorophyll b can sensitize the fluorescence of chlorophyll a, and that the fluorescence of chlorophyll b is more strongly quenched by a than it is by itself.

Effects of Solvent Upon Absorption Spectra of Chlorophylls A and B; Their Ultraviolet Absorption Spectra in Ether Solution

1. Solutions of chlorophyll a were prepared in thirteen solvents and of chlorophyll b in five solvents by direct elution from sucrose adsorption columns. 2. Absorption spectra for each solvent are reported as measured spectrophoto-electrically in the visible region. 3. Spectra for the ultraviolet region to 2650 A were determined for solutions in ethyl ether. 4. A preparation of dried chlorophyll a was made which retained excellent spectroscopic properties. 5. The application of Kundt's rule to chlorophyll solutions is discussed, as well as certain relations of spectroscopic properties and solvents to analytical applications.

An Improved Method for the Purification of Chlorophylls A and B; Quantitative Measurement of Their Absorption Spectra; Evidence for the Existence of a Third Component of Chlorophyll

1. An improved method for the isolation of chlorophyll components a and b has been developed. The methods of WILLSTATTER and STOLL and of TSWETT were combined and modified. The final purification processes involve differential adsorption on talc and fractional precipitation from petroleum ether, for components a and b respectively. The steps of the procedure are presented in detail. 2. The absorption spectra of chlorophylls a and b were measured accurately from λ 3950-7800 A. by a photoelectric method. Absorption coefficients at the maxima and minima were determined with an accuracy of 1.0%. The visible spectrum of each component consists of seven bands. 3. Spectral data indicate that the components prepared by WILLSTATTER and STOLL and by TSWETT were not separated completely from one another. The spectral method for detection of impurities is discussed. 4. A comparative study was made of the colors of a and b in various solvents and of certain chlorophyll derivatives. 5. Different tests of purity are dis...

Absorption Spectra of Chlorophylls a and b at Room and Liquid Nitrogen Temperatures

THE absorption spectra of ether solutions of chlorophylls a and b, prepared by the method described earlier1, were photographed at the temperature of liquid nitrogen. A Steinheil spectrograph and panchromatic plates were used for the spectral region 4100–6700 A. Pyrex glass absorption cells with internal thickness of 1 mm. contained the solutions. Four plane quartz windows in the walls of the Dewar vessel permitted parallel light to pass from the Mazda source through the liquid nitrogen bath and the solid solution of chlorophyll in ether, to the spectrograph slit. The slit width was 0.02 mm. The photographs were taken as soon as possible after freezing the solutions because the development of cracks in the solid ether solution caused it to become rather opaque in two hours.

The ultra-violet absorption spectrum of chlorophyll in alcoholic solution

Research Article| January 01 1928 The ultra-violet absorption spectrum of chlorophyll in alcoholic solution Elsa Lewkowitsch Elsa Lewkowitsch 1The Department of Chemical Technology, Imperial College of Science and Technology, S. Kensington Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1928) 22 (3): 777–778. https://doi.org/10.1042/bj0220777 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation Elsa Lewkowitsch; The ultra-violet absorption spectrum of chlorophyll in alcoholic solution. Biochem J 1 January 1928; 22 (3): 777–778. doi: https://doi.org/10.1042/bj0220777 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1928 CAMBRIDGE UNIVERSITY PRESS1928 Article PDF first page preview Close Modal You do not currently have access to this content.

A photographic investigation of the absorption spectra of chlorophyll and its derivatives in the violet and ultra-violet region of the spectrum

A photographic investigation of the absorption spectra of chlorophyll and its derivatives in the violet and ultra-violet region of the spectrum

Photographic investigation of the absorption spectra of chlorophyll and its derivatives in the violet and ultraviolet region of the spectrum

This is well known from the investigations of Soret, Gamgee, and others, hæmoglobin and its coloured derivatives show a characterics absorption band lying between the lines and M of the solar spectrum. The band has been shown to vary in position between narrow limits; in some derivatives it is nearer the red, and in others nearer the violet, end of the spectrum, and is of all the blood absorption bands the most stable.