A SENSITIVE METHOD FOR DETERMINING CHLOROPHYLL b IN PLANT EXTRACTS

Abstract— A new method of using hydroxylamine as the reagent was developed to determine the concentrations of chlorophylls a and b in plant extracts accurately and sensitively. The method is based on the principle that hydroxylamine reacts in a short time with the aldehyde group of chlorophyll b in 95 per cent methanol at pH 5.8 to afford a derivative having a red band similar in position to the red band of chlorophyll a , while the spectrum of chlorophyll a is unaffected by the treatment with hydroxylamine. The method includes the measurements of absorbanlce for the mixture of a plant extract with hydroxylamine and for the reagent blank at a single wavelength, 666 mμ, and the concentrations of chlorophylls a and b are calculated from the absorbance value for the reagent blank and the increment of absorbance due to the reaction. By measuring this increment directly by difference photometry, one can determine a low concentration of chlorophyll b relative to chlorophyll a . The contents of chlorophylls in matured and etiolated leaves were determined by the method, and the errors included in this method were shown to be smaller than those in a commonly used technique including the measurements at two different wavelengths.     

Some novel photosensitive diacetylene diurethanes and their mixtures in common polymers

Some new octa-3,5-diynylene diurethanes were prepared using 3-butyn-1-ol, and all were found to be highly light-sensitive and to undergo topochemical polymerization on exposure to irradiation. The di-n-octyldiurethane was mixed with vinyl polymers such as poly(vinyl acetate) and poly(N,N-dimethylamino-ethyl methacrylate) and the mixtures were made into thin films by spin coating. The films were then irradiated by an electron beam to polymerize the diacetylene. The purple films thus obtained showed third-order nonlinear susceptibility, χ⁽³⁾, of the order of 10⁻¹⁰–10⁻¹¹ e.s.u.     

Reduction of elemental selenium by samarium diiodide: Selective synthesis of diorganyl selenides and diselenides

The reduction of elemental selenium by samarium diiodide led to selective formation of selenolate anion species (Se²⁻ and Se₂²⁻), the alkylation of which provided dialkyl selenides and diselenides, respectively, in excellent yields.     

NMR studies on the ligand exchange reactions between diaryl tellurides and phenyllithium: Detection of hypervalent triaryl tellurium ate complexes

Diaryl tellurides undergo rapid ligand exchange and disproportionation reactions on treatment with phenyllithium at −78°C. Triarylteliuranes [10-Te-3(C₃)]⁻ Li⁺ were identified as discrete intermediates during the reactions by ¹²⁵Te, ¹H, ¹³C, and CH-COSY NMR studies.     

Metal-to-Oxide Charge Transfer Observed by a Kelvin Probe Force Microscope

The charge transfer from a nanometer-sized transition metal particle to a catalyst support is thought to affect reactions over the metal surface. We propose the application of Kelvin probe force microscope, which is an extension of the atomic force microscope, to observe the charge transfer particle-by-particle. Our recent results on Na adatoms, Cl adatoms, Pt adatoms and particles, and Ni particles evaporated on TiO₂(110) are reviewed.     

Generation and stabilization of ultrafast optical pulse trains with monolithic mode-locked laser diodes

In this paper, we report on the generation and the stabilization of ultrafast optical pulse trains exceeding 100 GHz from monolithic mode-locked laser diodes (MLLDs) combined with some new techniques such as subharmonic synchronous mode-locking (SSML) and repetition-frequency multiplication (RFM) method. Key subjects to increase the pulse repetition frequencies of the MLLDs such as fast absorption recovery and harmonic mode-locking operation are discussed. 500 GHz optical pulse generation from a short-cavity, graded-index separated confinement heterostructure MLLD and THz-rate pulse generation by harmonic mode-locking are reported. We also demonstrate the stabilization of a 160 GHz MLLD by the SSML with subharmonic-frequency optical pulse injection and reveal that the SSML is very promising as a stabilization technique of the ultrafast MLLD beyond the limitations by the electronic device speed. A method to accurately measure the timing jitter of such ultrafast optical pulse train, all-optical down converting using a nonlinear optical device, is also presented. We also mention another choice for ultrafast optical pulse generation using the MLLD combined with a dispersive medium such as an optical fiber. We demonstrate here the generations of stable 84–256 GHz optical pulse trains by the RFM method of the MLLD stabilized by the SSML.     

Reflection of a pulse by multiple-dielectric layers

The reflection of a pulse by multiple-dielectric layers is treated theoretically. The reflected wave is obtained by expanding the reflection coefficient of an elementary plane wave in a series, including the special case for which total reflection occurs. The pulsed waves reflected by two-dielectric slabs are considered in detail both analytically and numerically. The effect of a carrier frequency of a pulse-modulated carrier wave on the reflected wave form is also discussed.     

Ruby ESR Over a Wide Frequency Range in the Millimeter Wave Region

The ESR of Cr³⁺ in dark ruby is measured using a high frequency ESR spectrometer with a wide frequency range which uses a gyrotron as the radiation source. For this purpose, GYROTRON FU- IV A developed at Fukui University was optimized for use in an ESR apparatus operating in the millimeter-wave range.The observed fine structure constant D for ruby is found to be D –5.728 GHz and the g-values g 1.981, g 1.982. Both the values of |D| and g are smaller than those obtained at lower frequencies by other work. Higher order terms of the spin hamiltonian are discussed in order to understand the ruby ESR results in this higher frequency range.