Chemical Analysis by RAMAN Spectroscopy

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President & CEO
Rigaku Corporation

Rigaku Americas Corporation is pleased to announce the acquisition of the handheld Raman technology and product lines from BaySpec, Inc. and the concurrent formation of a new division, Rigaku Raman Technologies Inc., for R&D, engineering, production, marketing and distribution.

Rigaku's new handheld Raman instruments combine patented optics and proven spectral analysis techniques with state-of-the-art, low-cost Telecom-developed optical components, providing our customers with fast, economical, easy to use, handheld chemical identification and composition analyzers for explosives detection, including improvised explosive device (IED) detection; narcotics and other controlled substances detection and identification; counterfeit drug detection, food contaminant detection; and detection and identification of many other sample types; for homeland security; pharmaceutical, cosmetics, food, wine, beer and agricultural feed quality assurance and quality control; medical diagnostics; petrochemical exploration and process control; forensics; archeometry; and many other applications.

Led by Wes Hardenburg, as President and CEO, the new company is co-located in San Jose, California and The Woodlands, Texas. Initial offerings will comprise the FirstGuard™ and Xantus™ series product lines, covering sample excitation wavelengths of 532 nm, 785 nm and 1064 nm.

Raman spectroscopy (named after C. V. Raman), is a spectroscopic technique used to study vibrational, rotational, and other low-frequency modes in a system. It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range. The laser light interacts with molecular vibrations, phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down. The shift in energy gives information about the phonon modes in the system. Infrared spectroscopy yields similar, but complementary, information.

Typically, a sample is illuminated with a laser beam. Light from the illuminated spot is collected with a lens and sent through a monochromator. Wavelengths close to the laser line, due to elastic Rayleigh scattering, are filtered out while the rest of the collected light is dispersed onto a detector.

Spontaneous Raman scattering is typically very weak, and as a result the main difficulty of Raman spectroscopy is separating the weak inelastically scattered light from the intense Rayleigh scattered laser light. Historically, Raman spectrometers used holographic gratings and multiple dispersion stages to achieve a high degree of laser rejection. In the past, photomultipliers were the detectors of choice for dispersive Raman setups, which resulted in long acquisition times. However, modern instrumentation almost universally employs notch or edge filters for laser rejection and spectrographs (either axial transmissive (AT), Czerny-Turner (CT) monochromator) or FT (Fourier transform spectroscopy based), and CCD detectors.

There are a number of advanced types of Raman spectroscopy, including surface-enhanced Raman, resonance Raman, tip-enhanced Raman, polarised Raman, stimulated Raman (analogous to stimulated emission), transmission Raman, spatially-offset Raman, and hyper Raman.

Basic Theory

The Raman effect occurs when light impinges upon a molecule and interacts with the electron cloud and the bonds of that molecule. For the spontaneous Raman effect, which is a form of scattering, a photon excites the molecule from the ground state to a virtual energy state. When the molecule relaxes it emits a photon and it returns to a different rotational or vibrational state. The difference in energy between the original state and this new state leads to a shift in the emitted photon's frequency away from the excitation wavelength. The Raman effect, which is a light scattering phenomenon, should not be confused with absorption (as with fluorescence) where the molecule is excited to a discrete (not virtual) energy level.

If the final vibrational state of the molecule is more energetic than the initial state, then the emitted photon will be shifted to a lower frequency in order for the total energy of the system to remain balanced. This shift in frequency is designated as a Stokes shift. If the final vibrational state is less energetic than the initial state, then the emitted photon will be shifted to a higher frequency, and this is designated as an Anti-Stokes shift. Raman scattering is an example of inelastic scattering because of the energy transfer between the photons and the molecules during their interaction.

A change in the molecular polarization potential — or amount of deformation of the electron cloud — with respect to the vibrational coordinate is required for a molecule to exhibit a Raman effect. The amount of the polarizability change will determine the Raman scattering intensity. The pattern of shifted frequencies is determined by the rotational and vibrational states of the sample.

Chemical Analysis by RAMAN Spectroscopy

First Responders
Rapid identification of hazardous materials is RAMAN's forte. Hazmat teams, fire fighters, bomb squads and police officers require tools employ RAMAN to quickly identify unknown liquids and solids to determine whether they are hazardous or benign. Rapid identification helps minimize the risk and expedite remediation.

Military, Security and Governnment Agencies
Homeland security personnel tasked with preventing terrorist attacks use RAMAN to instantly identify dangerous materials and the precursors of biological agents, chemical weapons and narcotics. Applications include: IED / HME / WMD explosives detection, unknown substance identification, forensics analysis as well as Homeland Security (DHS), Border Patrol (BP) and transportation safety administration (TSA) screening.

Police and Law Enforcement
RAMAN delivers real-time identification of contraband and narcotics as well as gathering forensic evidence. Police, customs officers and security guards use RAMAN for identification of contraband and narcotics as well as gathering forensic evidence.

Incoming Material Inspection
Pharmaceutical and industrial manufacturing plants are moving toward 100 percent incoming material inspection to verify that the contents of a container are chemically authentic. RAMAN increases efficiency of the inspection process by enabling sampling through packaging, such as double-bagged pharmaceutical ingredients in a drum or tablets in blister packaging.

Process Control
RAMAN analysis is gaining acceptance as a process control tool. Since every molecule has a unique Raman signature, pure materials and blends can be uniquely identified at each stage of a production process without sample preparation. Low cost portable and benchtop RAMAN instruments enable new applications throughout process control environment that can not be served with the current technology. Specifically. the new generation of RAMAN spectrometers open the possibility of “at-line” and “near-line” process control for real-time analysis of foods, drugs and bulk materials.

Process Troubleshooting
RAMAN is unique in its ability to identify liquids and solids and the characteristic of materials as they change phase state (intermediates), without interfering in the reaction. This offers a unique opportunity to understand processes as they progress.

Chemicals Manufacturing and Use
Typical RAMAN applications include: incoming/outgoing materials inspection and certification; online/at-line detector for Process Analytical Technology (PAT); physical/chemical properties of polymers (molecular weight, viscosity, glass transition temperature, etc.); petroleum product identification and analysis; as well as the identification of resins, petrochemicals, and commodity chemicals.

Forensics
Examples of RAMAN applications include: non-destructive drug or chemical identification with preservation of evidence; identification of explosives; trace forensic analysis of fibers, hair, pigments, ink, fabrics, etc.; as well as solvents and bulk materials identification.

Mining, Minerals and Geology
Common RAMAN applications include: non-destructive identification of geological materials; authentification and anti-counterfeiting of gemstones; origin identification of minerals and gemstones; and the evaluation of mining prospects and alteration minerology.

Biological Sciences
RAMAN delivers in situ, non-contact, non-destructive measurement of tissue samples; intracellular chemical mapping; lipid content quantization in algae for biofuels; bacteria detection; and with optional Surface Enhanced RAMAN Spectroscopy (SERS), low level biological threat detection is also available.

Pharmaceutical and BioTechnology
Drug polymorphs/solvates may be identification and classified by RAMAN. In addition to the identification of unknown chemicals or pharmaceuticals, RAMAN can provide analysis of tablets, gel caps, and liquids through packaging. Other RAMAN applications include: QA/QC of API, additives, and excipients as well as high-throughput screening of raw materials or final products.

Food Safety and Agriculture
From port of entry inspections, to testing for pesticides and herbicides, to field audits for bacterial or chemical contamination, handheld RAMAN spectroscopy has proven itself as an invaluable analytical tool for everyday use.

Semiconductor and Thin Films
Examples of RAMAN applications include: wafer defect inspection; thin film coatings analysis; in-line at-line and near-line process inspection; as well as for quality control (QC) and quality assurance (QA).


Elemental Analysis by EDXRF Spectroscopy

Typical uses of EDXRF include the analysis of petroleum oils and fuel, plastic, rubber and textiles, pharmaceutical products, foodstuffs, cosmetics and body care products, fertilizers, geological materials, mining feeds, slags and tails, cement, heat-resistant materials, glass, ceramics, catalysts, wafers; the determination of coatings on paper, film, polyester; metals and alloys, glass and plastic; forensics; multi-layer thin films on silicon wafers, photovoltaics and rotating storage media as well as pollution monitoring of solid waste, effluent, cleaning fluids, pools and filters. In addition, X-ray Transmission (XRT) process gauges are employed to measure sulfur (S) in crude oil and marine bunker fuel.

Typical EDXRF Appplications
EDXRF spectrometers are the elemental analysis tool of choice, for many applications, in that they are smaller, simpler in design and cost less to operate than other technologies like inductively coupled plasma optical emission spectroscopy (ICP-OES) and atomic absorption (AA) or atomic fluorescence (AF) spectroscopy. Examples of some common EDXRF applications are: Cement and raw meal: sulfur, iron, calcium, silicon, aluminum, magnesium, etc; Kaolin clay: titanium, iron, aluminum, silicon, etc; Granular catalysts: palladium, platinum, rhodium, ruthenium, etc; Ores: copper, tin, gold, silver, etc; Cement and mortar fillers: sulfur in ash; Gasoline, diesel and RFG: sulfur, manganese, lead, etc; Residual gas oils: sulfur, chlorine, vanadium, nickel, etc; Secondary oil: chlorine, etc; Kerosine, naphtha: sulfur, etc; Crude oil and bunker fuels: sulfur, vanadium, nickel, etc; Plating, pickling & pre-treatment baths: gold, copper, rhodium, platinum, nickel, sulfates, phosphates, chlorides, etc; Acetic acid: magnesium, cobalt and bromine; Terephthalic acid (TPA): cobalt, manganese, iron, etc; Dimethyl terephthalate (DMT): heavy metals; PVC copolymer solutions: chlorine; Photographic emulsion: silver; Clay: metals and non-metals; Waste and effluent streams: RCRA metals, chlorides, phosphates, etc; Food, pet food and other animal feed: potassium, phosphorus and chlorine; Cosmetics: zinc, titanium, calcium, manganese, iron, silicon, phosphorus, sulfur, aluminum, and sodium; Wood treatment: CCA, Penta, ACQ, ACZA, phosphorus-based fire retardants, copper naphthanate, zinc napthanate, TBTO, IPBC and combinations of these; Antacids: calcium; and Toothpaste: phosphorus and tin.