Method for calorimetric absorption spectroscopy and device for working the method
First Claim
1. Method of calorimetric absorption spectroscopy, wherein a sample is irradiated with a measuring-light pulse of a specific power, duration, and wavelength, and the absorbance of a sample at the corresponding wavelength of the measuring light is determined from the heating of the sample which occurs as a consequence of absorption of a portion of the measuring light, characterized by the fact that the sample is held at a temperature at which its specific heat is only a small fraction of the value given at normal temperature (300 K.).
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Abstract
A method of calorimetric absorption spectroscopy (CAS) is claimed, wherein a sample, irradiated with a measuring-light pulse of a specified power, duration, and wavelength and whose absorbance at the specific wavelength of the measuring light is determined as a result of the heating of the sample which occurs as a result of the absorption of a portion of the measuring light, is cooled to a temperature which is so low that the specific heat of the sample during measurement is only a small fraction of the value at normal temperature. This produces an increase in sensitivity by a factor of more than 105. The manner in which the lifetime of radiant and nonradiant recombination can be determined in a simple fashion is claimed for samples which have a first impurity center, capable of recombination both by radiation and without radiation, and a second center, capable of recombination only without radiation. The temperature sensor in the sample chamber is placed in a cryostat suitable for working the method, and shielded hermetically against the measuring light and the scattered light resulting from the latter.
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11 Claims
- 1. Method of calorimetric absorption spectroscopy, wherein a sample is irradiated with a measuring-light pulse of a specific power, duration, and wavelength, and the absorbance of a sample at the corresponding wavelength of the measuring light is determined from the heating of the sample which occurs as a consequence of absorption of a portion of the measuring light, characterized by the fact that the sample is held at a temperature at which its specific heat is only a small fraction of the value given at normal temperature (300 K.).
- 10. A calorimetric absorption spectroscopy device, wherein a sample is irradiated with a measuring-light pulse of a specific power, duration, and wavelength, and the absorbance of a sample at the corresponding wavelength of the measuring light is determined from the heating of the sample which occurs as a consequence of absorption of a portion of the measuring light, comprising a helium cryostat for cooling the sample to a temperature between 1.5 K. to 0.3 K., wherein the cryostat has a heat-insulated cooling chamber for containing the sample, said chamber having an entrance window for the measuring light used to irradiate the sample, characterized by the fact that a temperature sensor is provided to detect the sample temperature, is mounted inside said cooling chamber and is shielded by a radiation shield against the incident measuring radiation, as well as the scattered radiation resulting from the latter.
Specification