| 摘要 |
PURPOSE:To enable exact measurement of the pH value of high temp. water which was heretofore difficult to be measured by forming a passivated film which exhibits the characteristic of an n type semiconductor stable even in high- temp. water to a metallic electorde and impressing bias voltage thereto while irradiating monochromatic light to the passivated film so that flat band potential can be easily measured. CONSTITUTION:An Fe electrode 3, a counter electrode 4 consisting of Pt for measuring the photocurrent to the electrode 3 and a reference electrode 5 for controlling the bias voltage between said electrodes are immsersed into the high- temp. water 2 in a pressure vessel 1. The electrodes are connected to a potentiostat 6 as a means for controlling the bias voltage. A differential amplifier 7 connected to the Fe electrode 3 and the counter electrode 4 is used to measure the potential difference between said amplifier and a resistor 8 and is connected via a lock-in amplifier 9 to a recorder 10. A transmission window 11 is provided to the side wall corresponding to the Fe electrode 3 of the vessel 1, and the monochromatic light from a 500W xenon lamp 16 is irradiated to the Fe electrode 3. |
