Have you ever found yourself intimidated by the complex world of physics and optics? Do equations and formulas leave you feeling overwhelmed, making you wonder if there’s a simpler way to understand these fundamental concepts? Dr. Daniel Andres-Penares, an expert in the field and application scientist at Specac, tackled these concerns head-on in his enlightening webinar titled “Is FT-IR Spectroscopy Really So Scary?”

In this captivating presentation, Daniel introduced himself and his academic background, setting the stage for an engaging exploration of spectroscopy. His mission? To demystify the often perplexing world of FT-IR Spectroscopy by promoting a “learning by doing, seeing, and experimenting” approach.

Brief:

Here are the brief of what were presented at the webinar:

  • Understanding Spectroscopy: A General Overview
    • What is Spectroscopy
    • Light and spectra: Specify MIR and its utility
    • what happens inside a spectrophotometer
    • Main concept of comparison with reference
  • Absorption: The Enigma of Different Materials
    • Explain transparency – bandgap concepts and examples 
    • Show with different crystals
  • Fingerprint peaks
  • Other techniques

View the webinar’s recording:

If you have signed up or attended the webinar, you would received the direct link in your email. If you didn’t have a chance to register for the webinar, you can get access to the recording by completing the following form:

Questions & Answers:

By the end of “Is FT-IR Spectroscopy Really So Scary?” Dr. Andres-Penares had transformed a potentially daunting topic into an accessible and engaging learning experience. We also had a very insightful questions and answers session, here are some of the questions we have received, you can find the answer here:

Question 1: Could you please elaborate on the choice of ATR crystals?
Answer: To determine which ATR crystals you can pick, there would be multiple factors to consider such as chemical compatibility, the required spectral range, and the refractive index of your crystal and sample. You can view our technical note: TN21-03 ATR Crystal Choice and Quest Puck Guide for a detailed explanation.

Question 2: Are there any realistic cases where total reflectance with the sample on the ATR crystal would not happen?
Answer: Yes, there are. ATR relies on internal total reflection within the ATR crystal, and that will only happen if the refractive index of the ATR crystal is higher than the to-be-measured material one. Hence, for solids or liquids with really high refractive index, the ATR crystal might not be suitable for that, and other crystal materials (or techniques) should be considered.

Question 3: Hi Dani is which method is more accurate Transmission or Reflectance?
Answer: Neither method is more accurate (by definition). The accuracy will ultimately depend on plenty of factors, such as the detector sensitivity, accuracy, the system stability… So those components will impact more on accuracy, rather than the technique itself. Both, transmission and reflectance, when used appropriately, offer the same level of accuracy with a proper post-analysis of the data. It’s important to recognize that ATR spectra and transmission spectra are not the same. Differences in peak positions and intensities between these two types of IR spectra need to be comprehended. The choice between these techniques should be based on factors such as the specific application, sample type, expected results, and the required experimental conditions, as both methods offer unique advantages. You can find out more here: FTIR – Transmission vs ATR spectroscopy | Animated Guides

Question 4: Do you have any recommended resources for learning how to more easily identify functional groups in samples of unknown compositions?
Answer: we have Infrared Frequency Lookup that can help. The provided lookup tool is designed to offer information regarding unidentified peaks within your IR spectrum. It encompasses a wide array of typical functional groups, each accompanied by their distinctive IR absorption frequencies, expressed in wavenumbers. Input the wavenumber corresponding to the peak you’re interested in within the designated field. Subsequently, the system will present potential matches, including the anticipated peaks, their respective intensities, and an estimation of when the peak is likely to occur, followed by the peak assignment.

Question 5: Hi, can you please elaborate on possible interferences with a ATR
Short Answer: Interferences shouldn’t affect ATR measurements when used properly.
Long answer: Interferences will appear every time there is more than one interlayer in the system. This can happen in various scenarios, such as between optical windows,… even within a lens. ATR crystals are not exempt of this.
However, it’s important to note that the presence of light interferences doesn’t necessarily translate into noticeable interference affecting your experiment – this is quite rare. To observe and have interferences impact your measurements, specific conditions must be met. For example, as discussed in the webinar, the interference frequency is entirely dependent on the separation between optical windows. If the distances between interfaces aren’t within the micrometre range, the interference will have a frequency that’s much larger or smaller, and it will barely affect your measurements.
In the case of single-bounce ATR crystals, where there are no plano-parallel interfaces, modal resonances might occur in highly specific crystal shapes. While unexpectedly encountering these situations is rare, in some cases, it’s intentional – through precise design and numerical simulations, one can predict when these resonances will occur. However, for standard ATR measurements using commercially available equipment, interferences should not arise solely due to the crystal. Nonetheless, it’s advisable to always be aware of optical windows within the system, just in case!

Upcoming Webinar in September

Make sure to check out our upcoming webinar on How to choose FT-IR Accessories hosted by Jeff D’Agostino, our Business Development Manager at 3 pm BST, Thursday, September 28th. All details about the webinar will be announced soon on our website!