The negative muonium ion Mu -= p+e e has been produced by double electron pickup as a beam of positive muons passes through a foil. A clean signal was detected by electrostatically accelerating and analyzing the ions in a magnetic time-of-flight spectrometer. The Mu beam at the focal plane of our spectrometer had an intensity 1.4x10 times that of the incident p+ beam or 2 s ', which corresponds to a Mu /p+ conversion probability of 0.5&10 at the foil in agreement with the calculated value. The kinetic energies of Mu at the foil are less than several keV as expected.

Improved lifetime with enhanced efficiency of an Alq 3 based OLED was realized by the co-evaporation of hexamethylbenzene (HMB). Two different solvated crystalline systems of Alq 3 , Alq 3 (C 7 H 8 ) 1/2 , Alq 3 (C 2 H 5 OH), were synthesized to investigate the effect of optically inactive materials on the emission properties of Alq 3 . Clathrate solvents perturb the excited electronic states of Alq 3 so that the incorporated materials in OLEDs should be chemically and optically inactive to control polymorphs. HMB acts as a carrier blocker for both electrons and holes. However, Alq 3 may be stabilized from Joule heat if the Joule heat is efficiently consumed as the vibrational/rotational energy of HMB. Consequently, the self-quenching and the crystallization of Alq 3 are effectively suppressed by the HMB, resulting in prolonged operating time and enhanced efficiency for Alq 3 -OLEDs. q