Studies on CO2 laser marking

The nature of CO₂ laser marking was studied with a view to putting these lasers to practical use in the semiconductor industry. The marking is found to be due to surface spattering rather than burning, which is the main factor in YAG laser marking. The visibility greatly increases by the application of a surface treatment such as marker ink, varnish or poster color. The CO₂ laser may therefore be used in place of the YAG laser, now widely used for marking, with some merits: CO₂ laser marking is cheaper and faster, and in addition there is no danger of injury from irradiating laser light.     

The intralayer order-disorder transition in monoclinic Cr3±xSe4

The Cr_3±xSe₄ shows an order-disorder transition from the monoclinic Cr₃Se₄ type to the CdI₂-type structure. This transition originates in the intralayer disordering of metal vacancies in the alternate partially filled metal layers along thec axis. The transition is reversible and of first order. The transition temperature vs composition curve has a maximum (～900°C) at a stoichiometric composition of Cr₃Se₄. A statistical treatment of this phenomenon was attempted via the Bragg-Williams approximation.     

Photocatalytic activity of ultra-fine rutile in methanol-water solution and dependence of activity on particle size

Ultra-fine rutile was prepared from titanium tetrachloride below 100°C and calcined in order to increase particle size. The effect of the particle size of the rutile on the photocatalytic activity in a methanol-water solution was observed in the range 120–1500 Å. The activity increased inversely with the diameter.     

Clustering effects of nucleonic matter in low-density region

We consider clusterized nucleonic matter with crystal structure which is described by Bloch function. By using Bloch function, we can describe two extreme states, isolated clusterized matter and uniform matter, in low and high density, respectively, and also intermediate states continuously. We treat not only α-cluster matter but also ¹⁰He-and ¹⁶O-cluster matter by introducing p-wave Bloch function orthogonal to s-wave Bloch function. P-shell cluster-like density fluctuation arises below a certain critical density as well as s-shell cluster-like one.     

Ultra-High Quality Cavity with 1.5 ppm Loss at 1064 nm

Characterization of an ultra-low loss and high finesse Fabry-Perot cavity at 1064 nm is reported. The characteristics are obtained from measurements of cavity decay time, frequency response and transmission efficiency. The results show that the mirrors have the loss of 1.5 ppm including absorption and scattering losses and the reflectance of 99.9873% which corresponds to a cavity finesse of 2.48X10⁴.     

Intramolecular orbital interactions in and conformation of N,N′-diphenylcarbodiimide studied by photoelectron spectroscopy

The intramolecular orbital interactions in N,N′-diphenylcarbodiimide were revealed by photoelectron spectroscopy and the phenyl rings in this compound were found to be twisted by ca. 25° from the perpendicular model.