At TSI, we manufacture a full line of individual aerosol generators and dispersers capable of producing monodisperse or polydisperse aerosols depending on your application.
TSI Aerosol Monitors offer real-time, direct-reading results, which is quickly becoming an industry best practice in occupational hygiene, indoor air quality, and outdoor environmental fugitive emissions monitoring.
Aerosol neutralizers are an essential piece of many aerosol research studies because aerosol particles dispersed by nebulization, combustion, or powder dispersion are usually electrostatically charged.
TSI Certifier® Gas Flow Analyzers are the trusted tool for biomedical testing professionals to improve efficiency in testing medical equipment, without sacrificing accuracy and reliability.
Leading the way in laser-induced breakdown spectroscopy (LIBS) for the lab and field.
For half a century, TSI has earned the reputation as a leader in designing and manufacturing flow measurement instrumentation. TSI mass flowmeters and mass flow sensors for gases are used worldwide in laboratory and manufacturing settings, plus embedded applications.
TSI serves fluid mechanics and particle diagnostics researchers with state of the art transducers, controls, software and complete measurement systems. Our instruments provide flow and particle information in a wide range of applications including aerodynamics, spray diagnostics, hydrodynamics, and more.
TSI’s Fume Hood Monitors and Controllers help you comply with the requirements and recommendations set forth in ANSI, ASHRAE, NFPA, and OSHA, which specify best practices fume hood performance and laboratory design.
For over 30 years, hospitals, laboratories, and cleanroom facilities have chosen TSI PresSura Room Pressure Monitors and Controls for monitoring of their critical environments.
Work environments, as well as homes and businesses, often require that people spend a majority of their time indoors. As a result, individual’s long term health and comfort is largely dependent upon indoor air quality testing. Businesses are increasingly interested
A revolution in light metals analysis, sorting, and recycling.
Full line of high-performance Raman spectrometers including handheld, portable, bench top and installed process control instruments.
Select from a broad range of particle counters, including those specifically designed for research, controlled environments and occupational/indoor air quality applications.
TSI's family of particle sizers is able to measure particles that span a broad size range, making them suitable for a wide range of applications.
PolyMax™ Plastics Analyzer changes the game in plastics identification, using laser-based technology to validate the chemistry of both light and dark plastic compounds — based on science, not best guesses.
From quantitative fit testing equipment to mask integrity testing equipment, TSI has respirator fit testing solutions to comply with regulated standards and help ensure your respiratory safety.
TSI's full line of industrial ventilation test instruments are designed to accurately and reliably measure a wide variety of parameters important in monitoring and maintaining indoor environments.
Airflow™ Instruments are accurate, high quality, professional-grade instruments used by a wide range of customers, including building service contractors, commissioning specialists, facility engineers and research professionals.
TSI manufactures high-quality Alnor® air velocity equipment. The Alnor brand of handheld instruments is widely used by HVAC contractors, facility personnel, building engineers, safety officers and industrial hygienists worldwide.
TSI offers state-of-the-art instrumentation for a variety of aerosol research applications.
In addition to requiring minimal maintenance and low cost of ownership, TSI’s air quality monitoring instrumentation is reliable, easy to use in the field for both long term and short term deployments, and features research level accuracy.
Laser Induced Breakdown Spectrometers (LIBS) and Raman Spectrometers for advanaced chemical and molecular analysis in the lab and field.
TSI provides a number of solutions for cleanroom applications, helping customers ensure regulatory compliance, enhance safety of products, and improve quality.
TSI has automated filter testers (AFTs) and components systems that are used to comply with various testing standards and regulations around the globe.
TSI's measurement solutions and knowledgeable staff can open up new understanding in your area of fluid mechanics and experimental research. Our products offer solutions in the areas of hydrodynamics, aerodynamics, spray diagnostics and more.
From biomedical testing to critical-space room pressure control, TSI provides a number of solutions specifically designed for hospital settings to enhance safety and efficiency.
TSI offers a full range of HVAC testing instruments that positively impact building occupant quality of life as well as improve energy efficiency of HVAC components.
Great for new and retrofit projects, TSI offers laboratory controls to match the requirements of a wide variety of applications.
Superior solutions for light metals analysis based on state-of-the-art laser technology.
TSI’s unique, real-time nanoparticle measurement instruments are relied upon by many professionals, including nanoparticle material and process researchers, inhalation toxicologists, industrial hygienists, and process engineers.
TSI occupational hygiene instruments help with the selection and implementation of effective workplace engineering controls, as well as the selection, use, and limitations of personal protective equipment.
Confident plastics analysis and identification solution for use throughout the plastics recycling life cycle.
Organizations worldwide rely on TSI CBRN defense products for reliable protection of personnel from chemical, biological, radiological or nuclear (CBRN) threats.
When a sample is illuminated with a laser and the scattered light is dispersed with a spectrograph, the output of the spectrograph will show a strong line at the excitation wavelength, and weaker lines appearing on both lower and higher frequencies of the strong line. Light scattered at the incident wavelength is called Rayleigh scattering. The shifted features are called Raman Stokes and Raman anti-Stokes lines, respectively, and have their origin in the interchange of energy between the light and the molecules causing the scattering. Because actual electronic or vibrational states are not accessed in this process, the frequency shifts observed in Raman spectroscopy are independent of excitation wavelength. The origin of the observed shifts relies on the property of polarizability. Polarizability is the relative tendency of a charge distribution to be distorted from its normal shape by an external electric field. It increases as the volume occupied by the bond electrons increases. In the classical explanation of Raman spectroscopy, the electric vector of the incident illumination induces an oscillating electrical dipole, by virtue of the bond’s native polarizability, which subsequently emits radiation. If the atoms in the molecule are not moving with respect to one another, the induced dipole, and therefore the scattered light, has the same frequency as the excitation laser. If the molecule is in motion, vibrating or rotating, the amplitude of the dipole will depend on the positions of the atoms within the sample molecule. In this case, the rotational and vibrational frequencies of the molecule will influence the scattered light such that the outgoing radiation consists of light of frequencies equal to the sum and difference between the incident beam and anti-Stokes and Stokes features. The quantum explanation is also related to a change in polarizability.
In both the classical and quantum descriptions of Raman scattering, actual scattering of light by molecules is governed by the relative polarizability of the electron distribution associated with the molecule. The Raman intensity is proportional to the square of the induced dipole moment (i.e. the square of the polarizability derivative). If the vibration does not appreciably change the polarizability, the induced dipole moment will be small, and the Raman emission feature weak.
In this description, the incoming photons promote the molecule into a higher lying energy state (usually a virtual state). The transition moment between the lower and higher states is the polarizability tensor. Energy available to the emitted, or scattered, photon is the energy of the excitation beam (ν0) plus or minus the vibrational state of the molecule prior to excitation (νvib). The scattered photons therefore have frequency of ν0+/- νvib. These processes are shown in Figure 1. The efficiency of Raman scattering is usually quite low; only about 1 out of every 106-108 incident photons is frequency shifted. Because near room temperature, most molecules are near their vibrational ground states, the signal intensity in the Stokes features is normally much larger than in the anti-Stokes. Indeed, for most applications, the anti-Stokes features are not even collected. (i.e. the electrons are shared unevenly between the atoms of the bond) before the arrival of the photon, such as C-O, N-O and O-H, are weak scatterers. Bonds that are relatively neutral, however, such as C-C, C-H and C=C, undergo large changes in polarizability during a vibration. These bonds have very active Raman features. This explains the strong Raman features of molecules with large pi bonds and ring structures, as well. Illustrative of this principle, a spectrum of benzene is presented in Figure 2. The feature at 992 cm-1 is the ring-breathing vibrational mode.
Molecular fluorescence is sometimes competitive with Raman scattering. If the material under test has a component with a real electronic energy level accessible by the Raman excitation beam, a portion of the excitation beam will be absorbed. The electronic energy level will, like the ground state, have a plethora of vibrational/rotational energy levels. A gradual descent through the vibrationally excited levels of the upper electronic state will occur (intra-system crossing), and then a photon will be emitted as the molecule relaxes into the ground state. Because of the large number of vibrational states in both the excited and ground states, the outgoing photons will be emitted in a wide array of frequencies, and therefore a broad band. The tail of this broad band can overlap the Raman shifts of interest, making strategies to deal with sample fluorescence of extreme importance in Raman spectroscopy.