Abstract: Apparatus for measuring breakdown plasma, comprising an irradiating device for irradiating a sample with a focused light beam and for causing breakdown of a ultrafine particle to be measured in the sample at the focused beam region to change the particle into plasma; a pair of electrodes arranged on opposite sides of the focused region of the beam; and a device for measuring an electrical resistance between the electrodes under a condition where the breakdown plasma is produced between the electrodes and for determining a diameter of the particle according to the measured electrical resistance serves for accurate measurement of the diameter of the ultrafine particle in the sample.

Abstract: By use of an excitation beam having a wavelength which is equal to, or close to, the sizes of particular particulate substances as the object of analysis, the particulate substances such as an immunoreaction product between an antigen and an antibody or between the antigen and a material supporting the antibody thereon are detected selectively. Very small particles having specific sizes such as rheumatuid factors, cancer specific antigens can be detected with high sensitivity.

Abstract: A method of and an apparatus for simultaneous determination of constituents are disclosed in which a solution containing trace constituents is irradiated with an intensity-modulated electromagnetic wave having a predetermined wavelength, a photoacoustic signal and radiation from the electromagnetic-wave irradiation trace constituents are detected together with the emission spectrum thereof. The concentrations of the trace constituents are calculated from the magnitude of the photoacoustic signal, the intensity of the radiation, and calibration curves each formed for known concentrations of one of the trace constituents, and the trace constituents are identified by the above emission spectrum.

Abstract: A dissolved substance contained in a solution is oxidized or reduced by adding a particulate semiconductor photocatalyst and a water-soluble electron acceptor or donor for the particulate semiconductor photocatalyst to a solution containing a dissolved substance, and irradiating the particulate semiconductor photocatalyst in the solution with an electromagnetic wave having an energy high enough to excite the particulate semiconductor photocatalyst, or by adding a particulate semiconductor photocatalyst and a water-soluble electron acceptor or donor for the particulate semiconductor photocatalyst to a solution containing a dissolved substance and irradiating the particulate semiconductor photocatalyst in the solution with an electromagnetic wave having an energy high enough to excite the particulate semiconductor photocatalyst and having a wavelength outside the absorption wavelength region of a precursor substance capable of producing an oxidation or reduction reaction-inhibiting substance, whereby (1) ions o

Abstract: A method for analyzing impurities in liquid and an apparatus therefor are disclosed, which are adapted to classify impurities contained in various liquids to be measured into soluble substance, insoluble substance and impurities in the form of bubbles and to measure their concentration separately; especially the impurities in liquid are analyzed by the method such that photoacoustic signals obtained by irradiating a liquid to be measured with intensity-modulated light are measured; the correlation between the modulation frequency of the intensity-modulated light (light modulation frequency) and the phase of the intensity-modulated light, with which the liquid to be measured is irradiated, as well as that of their photoacoustic signals are obtained; and impurities in the liquid to be measured are detected, while classifying them into soluble and insoluble ones and those in the form of bubbles on the basis of the information thus obtained; and the apparatus comprises a light source, at least one light modulator

Abstract: A medium including particles to be analyzed is contained in a cell through which excitation rays are passed. The excitation rays are focused and have a predetermined wave form. A period in time of the excitation rays is set substantially equal to and preferably longer than the attenuation time of an acoustic pulse which is generated when the excitation rays are absorbed in the particle and when the particle release heat. The acoustic pulse is used to analyze particle size and number of particles.

Abstract: A photoacoustic analyzer comprises an analyzing cell having a beam entrance window and including a cylindrical piezoelectric transducer element forming at least a part of the wall thereof, and a laser beam emitter emitting a laser beam directed toward and into the analyzing cell through the beam entrance window. In the photoacoustic analyzer, the ratio r/r.sub.o between the radius r of the inner side of the analyzing cell and the radius r.sub.o of the incident laser beam is selected to lie within the range of 1.ltoreq.r/r.sub.o .ltoreq.8.