High Frequency Deflection Measurement of IR Absorption with a Modulated IR Source
First Claim
1. A method of obtaining measurements of infrared absorption of sub-micron regions of a sample with a probe microscope employing a cantilever probe with a tip, the method comprising:
- a) illuminating a region of a sample with a tunable source of infrared radiation;
b) interacting the probe tip with a surface of the sample;
c) adjusting repeatedly a modulation frequency of the source of infrared radiation such that the modulation frequency substantially overlaps a resonant frequency of the cantilever probe and remains substantially overlapped as the cantilever resonant frequency shifts;
d) measuring a probe response resulting from absorption of infrared radiation by the sample;
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Accused Products
Abstract
A method of obtaining submicron resolution IR absorption data from a sample surface. A probe microscope probe interacts with the sample surface while a tunable source of IR radiation illuminates the sample-tip interaction region. The source is modulated at a frequency substantially overlapping the resonant frequency of the probe and may be modulated at the contact resonance frequency of the probe when the probe is in contact with the sample surface. The modulation frequency is continually adjusted to account for shifts in the probe resonant frequency due to sample or other variations. A variety of techniques are used to observe such shifts and accomplish the adjustments in a rapid manner.
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Citations
14 Claims
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1. A method of obtaining measurements of infrared absorption of sub-micron regions of a sample with a probe microscope employing a cantilever probe with a tip, the method comprising:
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a) illuminating a region of a sample with a tunable source of infrared radiation; b) interacting the probe tip with a surface of the sample; c) adjusting repeatedly a modulation frequency of the source of infrared radiation such that the modulation frequency substantially overlaps a resonant frequency of the cantilever probe and remains substantially overlapped as the cantilever resonant frequency shifts; d) measuring a probe response resulting from absorption of infrared radiation by the sample; - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 13)
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10. A method of obtaining measurements of infrared absorption of sub-micron regions of a sample with a probe microscope employing a cantilever probe with a tip, the method comprising:
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a. illuminating a region of a sample with a quantum cascade laser; b. interacting the probe tip with a surface of the sample; c. measuring a thermal tune of the cantilever probe to determine a contact resonant frequency of the cantilever probe d. adjusting a pulse frequency of the quantum cascade laser such that the pulse frequency substantially overlaps a resonant frequency of the cantilever probe; e. measuring a probe response resulting from absorption of infrared radiation by the sample. - View Dependent Claims (11, 12, 14)
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Specification