Gigahertz-repetition-rate, narrowband-deep-ultraviolet light source for minimization of acquisition time in high-resolution angle-resolved photoemission spectroscopy.

Ultrahigh-repetition-rate (1.1 GHz), deep-ultraviolet coherent light at 208.8 nm is generated by applying an external Fabry-Pérot cavity for repetition-rate multiplication to the fourth harmonics of a 10-ps, mode-locked Ti:sapphire laser. Its small pulse energy minimizes the unwanted space charge effect, while its high repetition rate drastically reduces the acquisition time in high-energy resolution angle-resolved photoemission spectroscopy using hemispherical electron analyzers. The absence of the space charge effect in the photoemission spectrum near the Fermi edge of polycrystalline Au at 8 K demonstrates this idea.

Observation of excitonic N-body bound states: polyexcitons in diamond.

We have found a series of resonances associated with the bound state (polyexcitons, PE(N)s) of N excitons up to N=6 in the emission spectra of diamond under two-photon excitation at around 10 K. Time-resolved spectra show a stepwise formation of PE(N)s with smaller to larger N, as well as a successive decay from larger to smaller N. At higher excitation levels, the transformation of PE(N)s into a condensed phase of electron-hole droplets occurs. The binding energies of the PE(N)s, normalized to the exciton Rydberg energy, agree well with those of silicon, suggesting the universality of the phenomena.

High-power, narrow-band, high-repetition-rate, 5.9 eV coherent light source using passive optical cavity for laser-based angle-resolved photoelectron spectroscopy.

We demonstrate a scheme for efficient generation of a 5.9 eV coherent light source with an average power of 23 mW, 0.34 meV linewidth, and 73 MHz repetition rate from a Ti: sapphire picosecond mode-locked laser with an output power of 1 W. Second-harmonic light is generated in a passive optical cavity by a BiB(3)O(6) crystal with a conversion efficiency as high as 67%. By focusing the second-harmonic light transmitted from the cavity into a ß-BaB(2)O(4) crystal, we obtain fourth-harmonic light at 5.9 eV. This light source offers stable operation for at least a week. We discuss the suitability of the laser light source for high-resolution angle-resolved photoelectron spectroscopy by comparing it with other sources (synchrotron radiation facilities and gas discharge lamp).

[The tentorial meningioma fed by "marginal tentorial artery" arising from the external carotid artery--a case report and review of literature (author's transl)].

It is well known that a Bernasconi-Cassinari artery is an important finding at diagnosis of the abnormality in tentorium. Since Bernasconi and Cassinari reported the artery in 1956, many reports have been presented and showed that the artery arose from the intracavernous portion of the internal carotid artery. We presented a 54-year-old female with tentorial meningioma. In selective external carotid angiography, the artery feeding the tumor was revealed arising from the accessory meningeal artery, which came off the internal maxillary artery and passed into the carnium through the foramen ovale, and took the same course of "Bernasconi-Cassinari artery". This angiographic finding suggests that it is possible for marginal tentorial artery to arise from an external carotid arterial system. It is said in the anatomical studies, when the trunk of primitive maxillary artery which is one of maxillo-carotid anastomotic arteries in fetus regresses, "marginal tentorial artery" usually remains linked to the internal carotid artery. But, if this transition of "the artery" from the external to the internal carotid artery failed, it is easily conceived the artery results in the origin of accessory meningeal artery, a branch of the external carotid artery.