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Title: High frequency alternating current chip nano calorimeter with laser heating

Heat capacity spectroscopy at frequencies up to 100 kHz is commonly performed by thermal effusivity measurements applying the 3ω-technique. Here we show that AC-calorimetry using a thin film chip sensor allows for the measurement of frequency dependent heat capacity in the thin film limit up to about 1 MHz. Using films thinner than the thermal length of the thermal wave (∼1 μm) at such frequencies is advantageous because it provides heat capacity alone and not in combination with other quantities like thermal conductivity, at least on a qualitative basis. The used calorimetric sensor and the sample are each less than 1 μm thick. For high frequency AC-calorimetry, high cooling rates at very small temperature differences are required. This is realized by minimizing the heated spot to the size of the on chip thermocouple (3 × 6 μm{sup 2}). A modulated laser beam shaped and positioned by a glass fiber is used as the heat source. The device was used to measure the complex heat capacity in the vicinity of the dynamic glass transition (structural relaxation) of poly(methyl methacrylate). Combining different calorimeters finally provides data between 10{sup −3} Hz and 10{sup 6} Hz. In this frequency range the dynamic glass transitionmore » shifts about 120 K.« less
Authors:
;  [1] ;  [2] ; ;  [1]
  1. Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18051 Rostock (Germany)
  2. (Germany)
Publication Date:
OSTI Identifier:
22220558
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 84; Journal Issue: 7; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALTERNATING CURRENT; BEAMS; CALORIMETERS; CALORIMETRY; ELECTRIC HEATING; FREQUENCY DEPENDENCE; FREQUENCY MEASUREMENT; KHZ RANGE; LASER-RADIATION HEATING; LASERS; METHACRYLIC ACID ESTERS; MHZ RANGE; SENSORS; SPECIFIC HEAT; THERMAL CONDUCTIVITY; THERMOCOUPLES; THIN FILMS