Methods, devices and kits for peri-critical reflectance spectroscopy

Abstract

Spectroscopy apparatuses oriented to the critical angle of the sample are described that detecting the spectral characteristics of a sample wherein the apparatus consists of an electromagnetic radiation source adapted to excite a sample with electromagnetic radiation introduced to the sample at an angle of incidence at or near a critical angle of the sample; a transmitting crystal in communication with the electromagnetic radiation source and the sample, the transmitting crystal having a high refractive index adapted to reflect the electromagnetic radiation internally; a reflector adapted to introduce the electromagnetic radiation to the sample at or near an angle of incidence near the critical angle between the transmitting crystal and sample; and a detector for detecting the electromagnetic radiation from the sample. Also, provided herein are methods, systems, and kits incorporating the peri-critical reflectance spectroscopy apparatus.

1 - 20 . (canceled) 
     
     
         21 . A method for detecting the spectral characteristics of a sample, comprising:
 placing a sample in proximity to a crystal;   serially introducing electromagnetic radiation from an electromagnetic radiation source to the crystal at a plurality of angles such that the electromagnetic radiation intersects a measurement site of the sample through a crystal at a plurality of angles of incidence, wherein the angles of incidence are incrementally changed between each introduction of the electromagnetic radiation;   detecting a reflected electromagnetic radiation from the sample at the plurality of angles of incidence with a detector; and   generating an angular map of the sample, wherein the angular map comprises a mapping of reflected electromagnetic radiation intensity relative to the plurality of angles of incidence.   
     
     
         22 . The method of  claim 21 , wherein the step of introducing the electromagnetic radiation comprises introducing the electromagnetic radiation at a first angle of incidence; and incrementally increasing the angles of incidence of electromagnetic radiation delivered to the sample to approach a second angle of incidence. 
     
     
         23 . The method of  claim 21 , wherein the step of introducing the electromagnetic radiation comprises introducing the electromagnetic radiation at a first angle of incidence; and incrementally decreasing the angles of incidence of electromagnetic radiation delivered to the sample to approach a second angle of incidence. 
     
     
         24 . The method of  claim 21 , further comprising the step of determining a critical angle between the crystal and the sample. 
     
     
         25 . The method of  claim 21 , further comprising the step of determining a depth of penetration of an evanescent wave into the sample at the plurality of angles. 
     
     
         26 . The method of  claim 25 , further comprising the step of generating a depth spectrum of evanescent wave absorption. 
     
     
         27 . The method of  claim 21 , wherein the step of generating the angular map further comprises plotting reflected electromagnetic radiation versus wavelength relative to a mapping of the angles of incidence. 
     
     
         28 . The method of  claim 21 , further comprising the step of comparing the reflected electromagnetic radiation to a database of critical angle measurements. 
     
     
         29 . The method of  claim 26 , further comprising the step of displaying a detected electromagnetic radiation parameter and one or more critical angle measurements from the database. 
     
     
         30 . The method of  claim 21 , wherein the step of emitting electromagnetic radiation from an electromagnetic radiation source further comprises collimating the electromagnetic radiation to have a beam divergence of one millidegree or less. 
     
     
         31 . The method of  claim 21 , wherein the step of introducing the collimated beam further comprises introducing the collimated beam to the sample through the crystal with an angular resolution of one millidegree or better. 
     
     
         32 . The method of  claim 21 , further comprising the step of imaging the reflected electromagnetic radiation onto a detector area less than 1 mm 2 . 
     
     
         33 . The method of  claim 21 , further comprising the step of modulating the electromagnetic radiation prior to introducing the electromagnetic radiation to the sample. 
     
     
         34 . The method of  claim 31 , further comprising the step of focusing the modulated electromagnetic radiation onto a reflector, wherein the reflector is adapted to introduce the electromagnetic radiation to the sample. 
     
     
         35 . A system comprising:
 at least one processor; and   a computer-readable medium storing one or more sequences of instructions which, when executed by the at least one processor, causes:   serially introducing electromagnetic radiation from an electromagnetic radiation source to a crystal at a plurality of angles such that the electromagnetic radiation intersects a measurement site of the sample through a crystal at a plurality of angles of incidence, wherein the angles of incidence are incrementally changed between each introduction of the electromagnetic radiation;   detecting a reflected electromagnetic radiation from the sample at the plurality of angles of incidence with a detector; and   generating an angular map of the sample, wherein the angular map comprises a mapping of reflected electromagnetic radiation intensity relative to the plurality of angles of incidence.   
     
     
         36 . The system of  claim 35 , wherein the instructions that cause introducing the electromagnetic radiation comprises instructions that cause introducing the electromagnetic radiation at a first angle of incidence; and incrementally increasing the angles of incidence of electromagnetic radiation delivered to the sample to approach a second angle of incidence. 
     
     
         37 . The system of  claim 35 , wherein the instructions that cause introducing the electromagnetic radiation comprises instructions that cause introducing the electromagnetic radiation at a first angle of incidence; and incrementally decreasing the angles of incidence of electromagnetic radiation delivered to the sample to approach a second angle of incidence. 
     
     
         38 . The system of  claim 35 , wherein the instructions that cause generating the angular map further comprises instructions that cause plotting reflected electromagnetic radiation versus wavelength relative to a mapping of the angles of incidence. 
     
     
         39 . The system of  claim 35 , further comprising instructions which, when executed by the at least one processor, causes determining a depth of penetration of an evanescent wave into the sample at the plurality of angles. 
     
     
         40 . The system of  claim 35 , further comprising instructions which, when executed by the at least one processor, causes comparing the reflected electromagnetic radiation to a database of critical angle measurements.