Variable thermodynamic raman spectroscopy system and method
Inventors
Schmidt, Walter F. • Kim, Moon S. • Chao, Kuanglin • Shelton, Daniel R. • Broadhurst, Catherine Leigh
Assignees
US Department of Agriculture USDA
Publication Number
US-9863882-B2
Publication Date
2018-01-09
Expiration Date
2036-02-01
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Abstract
The variable thermodynamic Raman spectroscopy method and apparatus is a system for material analysis. In operation, a target material is subjected to a variable thermodynamic protocol and analyzed using a differential scanning calorimeter.
Core Innovation
The invention is a variable thermodynamic Raman spectroscopy method and apparatus that analyzes material samples by subjecting a target material to a variable thermodynamic protocol and analyzing it using a differential scanning calorimeter. The system acquires Raman spectral data synchronized with temperature data during controlled heating or cooling of the sample, allowing the identification of molecular sites with different elastic responses to thermal stress.
The problem addressed is that conventional Raman spectroscopy provides steady-state measurements that cannot distinguish molecular sites of differing flexibility, as structurally different compounds can show similar Raman fingerprints. There exists a need for a method and apparatus that can quickly and reliably distinguish similar compounds and provide molecular structural information by identifying the most elastic sites within a material's molecular structure as they respond dynamically to temperature gradients.
Claims Coverage
The patent includes one independent system claim and an independent method claim, along with dependent claims detailing system components and operational ranges. The main inventive features relate to a sample analysis system integrating temperature measurement synchronized with Raman spectral acquisition and a method leveraging this system for variable thermodynamic analysis.
Sample analysis system with synchronized temperature and Raman spectral data acquisition
A system comprising a planar substrate with multiple elongated prongs supporting it vertically, a sample holder at the center, thermocouples positioned opposite the prongs to measure temperature, and a Raman probe directed at the target sample. The system synchronizes Raman spectral data acquisition with temperature data as the sample temperature changes, allowing recording of spectral data with corresponding temperature data.
Sample holder and heating configuration for controlled thermal analysis
A configuration where the substrate is circular and composed of copper with a cup-shaped sample holder attached through an aperture in the center. The prongs position the substrate on a heating device such that heat is conducted through the prongs to the sample, enabling heating and cooling cycles from approximately −200° C. to 400° C. The Raman probe directs a laser through the aperture to the sample and acquires spectral data during phase changes.
Method for acquiring variable temperature Raman spectral data synchronized with sample temperature
Providing the system and acquiring Raman spectral data as a target sample is heated or cooled through solid/liquid and liquid/gas phase changes, with spectral data synchronized to thermocouple temperature measurements. The method includes acquiring spectra at intervals less than 1° C. over a broad temperature range.
The claims collectively cover a system and method enabling real-time, temperature-synchronized Raman spectral acquisition during controlled thermal protocols, facilitating dynamic thermodynamic analysis of materials to identify molecular structural flexibility and phase transitions.
Stated Advantages
Enables rapid and reliable identification of compounds not readily distinguishable by conventional Raman spectroscopy.
Differentiates more elastic (temperature dependent) molecular sites from more rigid (temperature independent) sites.
Allows concurrent collection of thermodynamic phase transition and spectral information in real-time as a function of temperature.
Facilitates detection of chemical reactions and phase transitions through temperature-dependent spectral changes.
Supports analysis across a wide temperature range (approximately −200° C. to 400° C.), including cryogenic and high-temperature conditions.
Documented Applications
Rapid detection of food adulterants such as melamine, urea, biuret, and cyanuric acid in dry milk powder materials.
Authentication and quality evaluation of food ingredients through detection of contaminants and adulterants.
Macro-scale imaging of food and agricultural products, e.g., scanning cross-sections of tomatoes for maturity evaluation.
Investigation of molecular flexibility and phase transitions in peptides and small proteins, including dipeptides Ala-Pro and Pro-Ala.
Studying thermal transformation dynamics of proteins and biopolymers, including understanding protein thermal stability and unfolding.
Examining solid state and phase transitions of fatty acids and pesticides under varying temperature conditions.
Potential identification of environmental triazine contamination in soils and composts through differential temperature responses.
Material science and biochemistry applications involving the manipulation and engineering of molecules by understanding critical thermal behaviors and molecular flexibility.
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