Presentation on theme: "Overview of Raman Spectroscopy and portable markets Mark Schnittker 2013, Aug-23 408-368-1064."— Presentation transcript:
Overview of Raman Spectroscopy and portable markets Mark Schnittker 2013, Aug
Some common measurement techniques. Atomic techniques (usually inorganic) X-ray spectroscopy Optical absorption Plasma discharge Molecular techniques (usually organic) Chromatography Mass spectroscopy Vibrational Spectroscopy General Techniques Fluorescence Refractometry Reflectometry Absorbance IR resonanceScattering Resonance Trans FTIR Refl FTIR FTIR ATR Thermal Spectroscopy Raman spectroscopy FT Raman Surface Enhanced Raman (SERS)
How vibrational spectroscopy works Every molecule has vibrational modes (states). Vibrational modes = 3N-5 or 3N-6 pending the type of molecule where N=number of atoms “Group theory” determines which vibrational modes are “IR active”, “Scattering active”, or “forbidden”. Vibrational modes are quantized and will absorb photons of a specific energy (IR spectroscopy), or steal that same amount of energy from an incident photon and change the wavelength of the scattered photon (Raman spectroscopy).. FTIR and Raman spectrum of Glucose showing vibrational modes
What information is in the spectrum? Most of the identifying signatures are in the cm-1 range Carbonyl group in the cm-1 range is good at differentiating similar chemicals. With a good filter, raman can show lattice vibrational modes down at 200cm-1 which describes the physical structure of the sample. Harmonics Molecular rotation information Single Bonds Double Bonds Triple Bonds Carbonyl group Lattice vibrational modes 200cm-1 acetone ethanol Dimethyl sulfoxide Ethyl acetate toluene Raman of similar chemicals
Why is Raman spectroscopy “special”? Low cost optics High resolution arrays No water absorption Fluorescence NIR FTIR sees this region Water Absorption Mid IR Raman Bond information similar to FTIR Stokes Molecular Bond information is in this range Laser Visible Raman Scattering moves information to shorter wavelengths Anti-Stokes C.V. Raman
Attributes of Raman Spectroscopy -Consequences Probability of Raman scatter ~1E-6. –Needs lots of laser power –Can over heat samples which have low Raman activity and low thermal conductivity –Does not work well for trace detection (SNR of CCD) –Does not work well with low density samples (gasses) Avoids water absorption –Able to see many of the molecular resonances –Works well with aqueous solutions Probability of Raman scattering has dependencies (angular, temperature, ext) –Quantitative measurements are difficult –Raman is good at determining the presence of a molecule but not good at determining percentages. Centering based on available detectors and lasers –Has very low cost options –Fluorescence is often an issue Sensitive to polarizable bonds like C=C C=N, but less sensitive to dipoles like O-H, C-H, N-H –Needs good detector sensitivity in the cm-1 range.
Raman design trade offs Si detectors ~$50 with high pixel count High frequency lasers product too much fluorescence. Low frequency lasers “walk off” Si detector and reduce the available spectral range InGaAs detectors solve spectral range issues but are expensive and have reduced pixels=>lower spectral resolution. Raman spectral range Raman FTIR Raman
Portable Raman Markets overview Biological: Hydration, Glucose- needs good fluorescence removal. Must compete with transmission, fluorescent and low tech options. Homeland Security: Explosives and chemical agents detection. – needs built in chemical library Consumer products regulatory compliance: Detection of phthalates and other toxins in consumer products. –needs low cost and ease of use, and high SNR for trace detection. Law Enforcement: Narcotics Analysis –needs built in chemical library and authenticity certification Oil and Mining: Chemical /Mineral field analysis. Hazmat handling: First responders to accidents to evaluate threat – needs built in chemical library and sealed.
Portable Raman Markets overview Cont. Environmental: Field evaluation of contaminants in waterways and soils. These can also be permanently mounted modules in a distributed sensing network. –needs super weather tight and UV resistant housing Pharmaceuticals: Confirm shipments and mixtures through containers. – needs large spectral rang, carbonyl group detection. Defense: Combat troops to check for explosives and chemical weapons facilities –needs compact, light weight, battery powered, hermetically sealed Authenticity: Counterfeit detection of paintings, money, branded alcohol. –needs low fluorescence to see through glass Waste Management: Identification of reclaimed materials to determine proper recycling method –needs high speed, high efficiency to measure plastic fast without carbonizing it.
Process Raman Market. Process Raman uses small rugged modules which are connected via USB to send back spectrum insitu from the manufacturing line. Pharmaceuticals, plastics, petroleum, and chemical manufacturing companies are the final customers of process Raman. Example 1: Placing a small Raman module on the outside of a rotating drum to monitor the mixture of pharmaceutical chemicals Example 2: Leak detection. Sensor module mounted at each valve or potential leak point, per recent new regulation of hazardous emissions.
Key specifications (and how to engineer them) Fluorescence avoidance (Excitation laser, post process/fluorescence subtraction, feature-free spectral throughput, very good spectral throughput calibration) Spectral range (Excitation laser, Detector choice) Signal to noise (optical scattering, Laser power, detector dark current, electrical noise, integration time, optical throughput) Accuracy (temperature stabilization, calibration methods) Resolution (Spectrometer design, detector choice) Size, Weight, Ruggedness, Battery life. Need to see and know the peaks
Existing Portable Market Participants CompanyProduct, Average Selling Price MarketComments Laser Spectral range resolution Thermo Scientific First DefenderHomeland SecurityPurchased from Ahura for $140M in 2010, and now has the largest market share. 785nm 300mW cm cm-1 B&W TekNanoRam Pharmaceuticals and Toxins Awarded FDA contract over Thermo by being more willing to work with FDA. 785nm 300mW cm-1 <10 cm- 1 RigakuFirstGaurdPurchased from Bay Spec for undisclosed amount. Bayspec no longer allowed in handheld space. 532, 785, 1064nm 500mW cm cm- 1 IntevacPharma-ID Geology, Pharmaceuticals, Hazardous materials Purchased from DeltaNu in nm <100m W cm cm-1
Existing Portable Market Participants Cont. CompanyProduct, Average Selling Price MarketComments LaserSpectral Range Resoluti on Ocean Optics Pin Pointer General Purchased from Raman Systems 785nm mW cm cm-1 JascoRPM300 Authenticity. Art paintings Small volume specialty market Enwave Optronics EZ-Raman Defense Hazmat 785nm 300mW cm cm-1 OptoTraceRam TracerJapanese backed Chinese company with silicon valley operations.
Redox module is very compact. Designed for biological applications Optical Port Raman Module 65mm square Power/Data Cable Optional Li- Ion Battery Data processing and bluetooth transmitter Light weight molded optics with laser and integrated spectrometer Specs: cm-1 spectral range. ~10cm-1 resolution
Redox attributes in this market based on current product form. Small size and weightConnectivity over cellular to libraries Bluetooth enabledDynamically adjustable laser power High Signal to Noise RatioModule is “smart” with on-board processing. Scratch resistant optical contactInternal temperature stabilization Reliable-RuggedizedAuto proximity sensor for laser eye safety concerns Can be USB controlled Battery operated option Sealed
Investigating technical needs of a market segment Partner with a customer which can test efficacy of a system. Many chemicals have been cataloged in Raman databases. To investigate a market, find out what chemicals are involved in that market and pull up their spectrum. Evaluate what spectral range and resolution would be needed to identify the chemical.. acetaminophen Minerals
Want to get measurement in-house?. Portable RamanResearch grade Fiber coupled Too integrated. Not flexible enough Too expensive and requires skilled operator Good match. Flexible, and less expensive Home brew: Most flexible. Good if you have in house expertise. Make a cheap fluorescence set up and explore excitation wavelengths before investing in a Raman system.
Thanks Mark Schnittker Market development specialist contractor for Redox