While many people often use spectroscopy and spectrometry interchangeably, there are some subtle differences in their exact meanings and the associated experimental techniques they are used to describe.
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The International Union of Pure and Applied Chemistry’s (IUPAC) Gold Book – the ‘Compendium of Chemical Terminology’ – defines spectroscopy as ‘the study of physical systems by the electromagnetic radiation with which they interact or that they produce.’1
The corresponding IUPAC Gold Book definition of spectrometry is: ‘spectrometry is the measurement of such radiations as a means of obtaining information about the systems and their components’1
What does this mean in practice for spectrometry vs spectroscopy? Normally, spectroscopy is used to refer to any of the family of experimental methods that use electromagnetic radiation, which includes: optical, infrared, nuclear magnetic resonance (NMR) and Raman.
Spectrometry is typically used to refer to methods like mass spectrometry – in mass spectrometry, it is the fragmentation pattern of the sample that is used to analyze its properties rather than its direct interaction with electromagnetic radiation.
What are the differences in the history and use of spectroscopy vs spectrometry approaches? Both families of methods have long histories, with the earliest spectrometry experiments with cathode ray tubes being performed in the 1850s, and the beginnings of spectroscopy arguably being when Issac Newton first used a prism to separate white light into its component colors.2,3 Now, both techniques are widely used in research and industrial laboratories around the world, and are often complementary to each other.
Spectrometry Vs Spectroscopy: Methods
What are the key differences in spectrometry vs spectroscopy instrumentation? Both types of measurement make use of a spectrometer – but the designs are quite different. In spectroscopy, a typical spectrometer will consist of a light source and a detector, often with a number of optical components to manipulate the electromagnetic radiation. Depending on whether one or multiple wavelengths are to be recorded at a time, the detector may be a simple photodiode or some kind of array detector, like a CMOS camera.
For spectrometry vs spectroscopy, the instrumentation is designed very differently. In a spectrometry vs spectroscopy measurement, it is charged particles that are instead detected – typically ions in the case of mass spectrometry. A mass spectrometer, therefore, has some kind of ionization source to induce fragmentation in the sample of interest, and a charged particle detector such as a combination of phosphor screens and multichannel plates or channel electron multipliers. There often needs to be additional electromagnetic fields in a spectrometry vs spectroscopy experiment to control the trajectories of the charged particles and ensure they reach the detector correctly.
Spectrometry Vs Spectroscopy: Properties
When it comes to deciding on spectrometry vs spectroscopy as a solution to your scientific problem, the choice often depends on what information needs to be recovered. Both techniques can be used for qualitative and quantitative analysis on samples and are compatible with a variety of sample types, including biological samples, liquids, gases etc. Specific instrumentation and sample delivery systems may be required to handle some samples or make some measurements more challenging, but both are generally quite flexible techniques.
The disadvantage of spectrometry vs spectroscopy is perhaps for applications where information on the electronic structure of the material or sample is of key interest. Spectroscopy has been described as ‘applied quantum mechanics’ and the right spectroscopic technique can recover relatively direct information on the electronic configuration of a sample. For example, UV-vis absorption spectroscopy is ideal for screening many optoelectronic materials as it allows for relatively easy measurement of the HOMO-LUMO separation, which is often a key design parameter.
Spectrometry vs spectroscopy does not allow such direct access to information on the quantum mechanical properties of samples but may be better suited to sample identification. While some families of spectroscopic methods do produce what are known as ‘fingerprint’ spectra – spectral features sufficiently distinct they can be used for compound identification – such as infrared spectroscopy5, for complex sample analysis including of mixtures, when choosing mass spectrometry vs spectroscopy, spectrometry may be the better option.6 Mass spectrometry vs spectroscopy instrumentation is also very matured and widely used so there may be more commercial options available.
Spectrometry Vs Spectroscopy: Applications
Nearly all areas of industry make use of spectrometry or spectroscopy and whether spectrometry vs spectroscopy is the right choice is heavily case dependent. In nanotechnology, tailored mass spectrometers can be used for analyzing growth processes in ultra-high vacuum chambers for sample preparation or profiling the composition of thin film layers.
Spectroscopy, on the other hand, is useful for understanding how a nanoscale sample will interact with light and what its optical properties and responses might be.
Spectrometry Vs Spectroscopy: Commercial Landscape
For spectrometry vs spectroscopy, both the commercial landscapes look positive and set to grow. Pharmaceuticals, aerospace, food manufacturing, security and defense all rely on spectrometry or spectroscopy methods for sample identification and analysis.
Commercial instrumentation for spectrometry versus spectroscopy is typically more expensive, but there are many suppliers available for a number of different measurement types and constant innovations on the market for better-resolving power or more complex alternative forms of the technique, such as hyphenation to recover more chemical information. Both spectrometry and spectroscopy are key to many of the analytical sciences and future technical developments.
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References and Further Reading
IUPAC (2022) Gold Book, https://goldbook.iupac.org/terms/view/S05848
Smoluch, M., & Silberring, J. (2019). A brief history of mass spectrometry. Mass Spectrometry: An Applied Approach, pp.5–8. doi.org/10.1002/9781119377368.ch2
Thomas, N. C. (1991). The early history of spectroscopy. Journal of Chemical Education, 68(8), pp.631–634. doi.org/10.1021/ed068p631
Ball, D. W. (2007) Spectroscopy is Applied Quantum Mechanics, https://www.spectroscopyonline.com/view/spectroscopy-applied-quantum-mechanics-part-i-need-quantum-mechanics,
Sorak, D., et al. (2012). New developments and applications of handheld raman, mid-infrared, and near-infrared spectrometers. Applied Spectroscopy Reviews, 47(2), pp.83–115. doi.org/10.1080/05704928.2011.625748
Cunsolo, V., & Foti, S. (2019). Mass spectrometry in proteomics. Mass Spectrometry: An Applied Approach, pp.261–272. doi.org/10.1002/9781119377368.ch8
