Frequently Asked Questions
Portable Raman FAQs
Q: What is Raman spectroscopy?
A: Raman spectroscopy is a form of molecular spectroscopy which is observed as inelastically scattered light when a sample is excited by a laser source. The Raman scattered light shifted by the interaction with the molecular bonds, resulting in a spectrum that allows for identification of vibrational (phonon) states of molecules. As a result, Raman spectroscopy provides an invaluable analytical tool for molecular fingerprinting as well as monitoring changes in molecular bond structure. These changes can be due to formation and breaking of molecular bonds as during chemical reaction, change in crystalline form from one polymorph to another, or changes in the energy of bonds such as may arise from stress and strain on a material.
Q: What type of samples can I measure with a portable Raman instrument?
A: Our portable Raman instruments can be used for the measurement of liquids and solids. The standard sampling probe included with i-Raman series instruments can be used for direct contact to a solid, or interfaced to a transparent container to measure liquids. A selection of sample accessories is available for optimal sampling of liquids in a cuvette or liquid vial, or directly with an immersion probe. Solids can be measured in contact, or through a video microscope, or at a distance with a zoom lens. Read more information about these accessories here.
Q: Which laser wavelength should I use for my Raman analysis?
A: There are models of the i-Raman Series instruments with laser excitation of 532 nm, 785 nm and 1064 nm. The most common of these with the greatest versatility for a large variety of samples is 785 nm excitation. Generally 532 nm excitation Raman is good for carbon materials and biologics, 785 nm is good for majority of substances, and 1064 nm is good for colored and darker materials, as this longer wavelength has less fluorescence which can interfere with the Raman spectrum especially for these types of samples. Read our application note on choosing the best laser wavelength.
532nm Laser/System:
Q – If the interlock is pulled out and the laser is turned off, how much time is needed for the laser to stabilize when the laser turns back on?
A – Approximately 30 seconds is needed for the laser to stabilize after the laser starts emitting energy.
*Some older generation probes may not block the entire laser signal. A simple test can be
done by increasing the exposure time, leaving the laser on, switching the shutter on the probe
to off and then taking a scan to see if any laser signal is present.
785nm Laser/System:
Q – If the interlock is pulled out and the laser is turned off, how much time is needed for the laser to stabilize after the laser turns back on?
A – Approximately 2-5 seconds is needed to for the laser to stabilize after the laser starts emitting energy.
Q – Can my Raman Probe be used to take a dark scan by simply closing the shutter on the probe?
A – Yes, the dark scan can be taken by closing the shutter on the probe. It is also recommended to turn off or otherwise block ambient light when measuring Raman signals.
*Some older generation probes may not block the entire laser signal. A simple test can be
done by increasing the exposure time, leaving the laser on, switching the shutter on the probe
to off and then taking a scan to see if any laser signal is present.
Q – What is the recommended way to measure a solid sample?
A – In order to measure a solid sample, place the Raman probe shaft with the distance regulator directly in contact with a sample to collect the Raman spectrum. The distance regulator is designed for optimal focus and to also exclude extraneous light from the measurement.
Q – Can I measure liquids directly?
A – An immersion probe shaft is needed to make measurements in a liquid sample. Liquids can also be measured through a glass vial or a cuvette. We offer a liquid vial holder (NR-LVH) and a cuvette holder (BCR100A) designed for use with the i-Raman® series lab probes.
Q – Can I do Raman microscopy with a portable Raman?
A – The i-Raman® series instruments can be used with the BAC151 series video microscopes which have an integrated camera and are readily interfaced with the fiber-optically coupled probe. This setup provides precision microsampling through camera monitoring and imaging details.
Q – Can I use my i-Raman® Plus for fieldwork?
A – The i-Raman series instruments are portable, with the i-Raman Plus weighing less than 7 lbs. The system is battery operable and can be used with a range of sampling accessories including a tripod for use in the field.
Q – Does BWSpec® software provide tools to optimize data collection?
A – All the data acquisition software for our portable Raman instruments, BWSpec®, BWID®,BWAnalyst®, and Vision® used with the i-Raman series instruments have auto-integration time functions that will optimize the acquisition time to give optimal signal intensity.
Q – What is the recommended way of collecting the Raman spectrum of a delicate or heat sensitive sample?
A – The laser power can be adjusted down to 1% laser power (< 5mW). Using low laser power is recommended for measurements of delicate samples to minimize the risk of sample damage.
