Setup for the temperature-jump method with nanosecond heating
Abstract Generated abstract
A temperature-jump apparatus for studying fast reactions in solution is described, designed to achieve pulsed heating on a nanosecond time scale. The setup combines a high-voltage power supply, pulse-forming cable line, pressurized nitrogen spark gap, monochromator, thermostated quartz-window cell, photomultiplier detection, and oscillographic recording, with measures to reduce noise and improve discharge characteristics. Its heating time is reported as 80 ns, substantially shorter than typical capacitor-discharge temperature-jump systems cited by the authors. As a test application, dissociation and recombination rates of acetic acid measured using bromocresol green agreed well with previously reported values.
Full Text
Proceedings of the Tomsk Polytechnic Institute Named after S. M. Kirov, Holder of the Order of the October Revolution and the Order of the Red Banner of Labor
Vol. 257 1973
Temperature-Jump Method Setup with Nanosecond Heating
V. T. Novikov, V. L. Ivasenko, V. P. Lopatinskii
The study of fast reactions in solution by the temperature-jump method (TJM) is based on pulsed heating of the solution under investigation and on recording the time during which the system reaches a new equilibrium state [1]. A temperature jump can be produced by a pulse of passing current, a laser flash, or a microwave pulse. The heating time in these setups is \(10^{-5}\)–\(10^{-4}\) sec. The most widely used TJM apparatus employs the discharge of a high-voltage capacitor through a cell.
The authors have developed a setup with a heating time of 80 nsec, consisting of a power supply, a pulse-forming line, a spark gap, a monochromator, a cell, and a recording circuit.
The power supply consists of a step-up transformer (IOM-10/25), a high-voltage kenotron whose filament is powered by a specially made transformer, and a bank of three KBG-P capacitors (0.1 μF each).
The pulse-forming line consists of 10 meters of RK-100 cable. The spark gap is made of duralumin. Its operating principle consists in mechanically bringing one electrode closer to the other until a discharge occurs. To reduce the structural dimensions and improve the electrical characteristics of the spark gap, nitrogen is pumped into the interelectrode space up to 15 atmospheres. For the same purpose, the leads of the spark-gap cable are shortened and, to prevent breakdown, filled with transformer oil. An SF-4 spectrophotometer is used as the monochromator.
The thermostating cell is made of fluoroplastic with optical windows of fused quartz.
The recording circuit consists of FEU-18A (220–600 nm); FEU-36 (300–700 nm) and S1-13 and S1-19 oscillographs.
To reduce FEU noise, VAS-T-80-21 batteries are used as the FEU power supply.
Using bromocresol green as an indicator, the rates of dissociation and recombination of acetic acid were measured on this setup; they were found to be \(1.3 \cdot 10^6\ \mathrm{s}^{-1}\) and \(7.3 \cdot 10^{10}\ \mathrm{m}^{-1}\mathrm{s}^{-1}\), which is in good agreement with those obtained previously.
References
- E. Kolpin. Fast Reactions in Solutions. “Mir,” 1961.