We provide an overview of the fundamental units of physical quantities determined naturally by the values of fundamental constants of nature. We discuss a comparison between the "Planck units", now widely used in theoretical physics, and the pre-quantum "Stoney units" in which, instead of the Planck constant, the charge of the electron is used with very similar quantitative results. We discuss some of the hindsight physical motivation for such units, and also put forth a summary of the arguments supporting various cases for making specific physical interpretations of the meanings of some of these units. The new aspects we discuss are a possible physical basis for the Stoney units, their link to the Planck units, and also the importance of Planck units for thermodynamical quantities in the context of quantum gravity.
The decay time of the phosphor YAG:Ce is temperature dependent. Selective incorporation of gallium into the YAG:Ce matrix permits tuning the temperature at which quenching begins. Also, the size of the phosphor particle and processing method affect this characteristic. We describe one such situation in which quenching of the combustion synthesized nanophosphor Y 3 (Al 0.5 Ga 0.5) 5 O 12 :Ce 1% was observed from ambient to 125 C. By signal averaging of laser excited fluorescence, temperature uncertainties ranged from 0.05 to 0.15 C. The single shot temperature uncertainty at 115 C was ± 3 C, indicating the feasibility for transient thermometry with response rate exceeding 1 MHz.
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