Method and apparatus for modulated differential analysis
AssigneeTA Instruments, Inc.
InventorsMichael Reading, Brian K. Hahn, Benjamin S. Crowe
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Abstract
The present invention relates to differential analytical techniques for determining the composition, phase, structure, identification or other properties of a material that undergoes a transition as function of a driving variable. As applied to differential scanning calorimetric analysis (DSC), the preferred embodiment comprises: (1) heating a sample of the material with a linear temperature ramp that is modulated with a sinusoidal heating rate oscillation; and (2) deconvoluting the resultant heat flow signal into rapidly reversible and non-rapidly reversible components.
Claims55
A method for analyzing a material that undergoes a transition as a function of temperature comprising the steps of:
- (a) selecting an underlying rate of change of the temperature;
- (b) selecting a modulation function;
- (c) selecting a modulation frequency;
- (d) selecting a modulation amplitude;
- (e) placing a sample of the material in an apparatus for detecting differential changes in a characterizing physical parameter of the sample with respect to a reference as a function of the temperature of the sample;
- (f) varying the temperature of the sample according to the selected underlying rate of change of the temperature, the selected modulation function, the selected modulation frequency and the selected modulation amplitude;
- and
- (g) recording a differential signal representative of differential changes in the characterizing physical parameter.
An analytical apparatus comprising:
- (a) means for varying the temperature of a sample at an underlying rate of change;
- (b) means for selecting a modulation function, a modulation frequency and a modulation amplitude;
- (c) means for modulating the temperature of the sample according to the selected modulation function, modulation frequency and modulation amplitude;
- (d) means for detecting a signal representative of differential changes in a characterizing physical parameter of a sample with respect to a reference as a function of the temperature, as the temperature is varied according to the underlying rate of change of the temperature, and modulated according to the modulation function, the modulation frequency and the modulation amplitude;
- and
- (e) means for recording the signal representative of differential changes in the characterizing physical parameter.
A method for analyzing a material that undergoes a transition as a function of a driving variable comprising the steps of:
- (a) placing a sample of the material in an apparatus for detecting differential changes in a characterizing physical parameter of the sample with respect to a reference as a function of the driving variable;
- (b) varying the driving variable at an underlying rate of change modulated by a modulation function, said modulation function having a preselected modulation frequency and a preselected modulation amplitude;
- (c) monitoring a differential signal representative of differential changes in the characterizing physical parameter;
- (d) controlling the underlying rate of change of the driving variable according to changes in the differential signal representative of differential change in the characterizing physical parameter;
- and
- (e) recording the differential signal representative of differential changes in the characterizing physical parameter.
A method for analyzing a material that undergoes a transition as a function of pressure comprising the steps of:
- (a) selecting an underlying rate of change of pressure;
- (b) selecting a modulation function;
- (c) selecting a modulation frequency;
- (d) selecting a modulation amplitude;
- (e) placing a sample of the material in an apparatus for detecting differential changes in a characterizing physical parameter of the sample with respect to a reference as a function of pressure;
- (f) varying the pressure according to the selected underlying rate of change of pressure, the selected modulation function, the selected modulation frequency and the selected modulation amplitude;
- and
- (g) recording a differential signal representative of differential changes in the characterizing physical parameter.
An analytical apparatus comprising:
- (a) means for varying the pressure on a sample at an underlying rate of change;
- (b) means for selecting a modulation function, a modulation frequency and a modulation amplitude;
- (c) means for modulating the pressure according to the selected modulation function, modulation frequency and modulation amplitude;
- (d) means for detecting a signal representative of differential changes in a characterizing physical parameter of a sample with respect to a reference as a function of the pressure, as the pressure is varied according to the underlying rate of change of the pressure, and modulated according to the modulation function, the modulation frequency and the modulation amplitude;
- and
- (e) means for recording the signal representative of differential changes in the characterizing physical parameter.
Dependencies are inferred from the claim text.