top of page

Environmental Application of Photoelectron Spectroscopy and Mass Spectroscopy

Before getting into the details about photoelectron spectroscopy and mass spectroscopy, we have to understand what the term, “spectroscopy” means. Spectroscopy is a technique that uses electromagnetic radiation to obtain information on the structure and properties of matter (”Basic Spectroscopy”). Based on this we can infer that mass spectroscopy will tell us mass-related molecular information and photoelectron spectroscopy will reveal how the ejection of electrons by photon affect the properties of matter.


Definitions for each spectroscopy are:

Mass spectroscopy = “The most direct and accurate method for determining atomic and molecular masses” (Chang).

Photoelectron spectroscopy = “An experimental technique that measures the relative energies of electrons in atoms and molecules” (”Photoelectron Spectroscopy”).


So how does mass spectroscopy work?

(”Isotopes and…”)

Methods:

  1. First, a sample of electron is added to the other side of the detector.

  2. The electron is vaporized with heat and are bombarded with numerous electrons through the electron beam.

    1. Remove electrons from the atom and the atoms are ionized.

  3. Now the atoms have charges and through the electric plates, the ions accelerate.

  4. The ions are deflected through the strong magnetic field.

    1. Larger mass = less deflection

    2. Lighter mass = more deflection

    3. * the force of deflection is equal for all ions Each deflected isotope is located at different position on the deflector.

  5. Using this information , a graph is created to visualize the data (“Mass Spectrometry”).

    1. Utilizing this graph, we can apply to analyze different environmental factors, such as effects of pesticides, marine toxins, etc. (”Mass Spectrometry Applications for Environmental Analysis”)

Next up is the photoelectron spectroscopy. But, before getting into the photoelectron spectroscopy, we have to understand the theory of “photoelectric effect” by Albert Einstein.

The photoelectric effect is a phenomenon that surface electrons on metals are emitted when electromagnetic radiation hits an atom (Edmerls).

If you know this concept, you got half of the idea of what photoelectron spectroscopy is. This is because the main concept of photoelectron spectroscopy is applying the idea of photoelectric effect to free atoms and molecules instead of metals.

(”Electron Spectroscopy”)


Then how does photoelectron spectroscopy work?

Methods:

  1. High energy radiation, like UV light and X-rays, bombards a sample, resulting in the ejaculation of electrons from the sample

  2. The ejected electrons travel to the energy analyzer

    1. The energy analyzer records the kinetic energies of the electrons

  3. From the energy analyzer, the electrons travel to the detector

    1. The detector counts the number of photoelectrons at various kinetic energy (“Photoelectron spectroscopy”)

    2. Using this detector, visuals like graphs can be produced, which can be used in analyzing the surface of nano-complexes, comparing element composition of certain samples, etc.


So how does the analysis work?


Mass Spectroscopy:

(Choi, Choi et al)

Mass spectroscopy allows scientists visualize the mass-to-charge ratio (m/z) of the sample and its relative abundance of isotopes in the sample.


Application of this technique to analyze environmental factors can help the agricultural scientists to know what kind of element destroyed certain crops or determine what sort of element in pesticides killed certain insects. Mass spectroscopy is a huge help in determining these information because it tells the analyzers to know the percentages of isotopes in a sample, which the scientists will be able to predict the most effective and abundant isotope in the sample.


For the figure above, you can see that in a sample of quinine (C20H25O2N2), quinine-325.1856 is the most abundant and this isotope might be the reason for certain phenomenon that scientists are trying to discover.


Photoelectron Spectroscopy:

(”AP Chemistry: Photoelectron Spectroscopy”)

Scientists use photoelectron spectroscopy to study the elemental composition of materials or to characterize bonding in molecules by finding the binding energy (MJ/mol) and the number of photoelectrons.


Using this information, we can compare multiple samples easily and determine their elemental composition, empirical formula, chemical state and electronic state of the elements that exist within a material (”ESCA”). This allows many biologists to apply the technique to the nature to find out chemical properties of samples from the environment and find out what specific elements are in certain organisms.

As we can see, spectroscopies make our lives much easier and safer by allowing the scientists to accurately estimate the elemental compositions that will help to solve certain problems that professionals are trying to make changes in.


References:

Chang, Raymond, and Jason Overby. Chemistry. New York, United States, McGraw-Hill Education, 2021.


Choi, Jaewon, et al. Fast and Accurate Identification of Pesticides by Direct Analysis in Real Time (DART) Ionization With Orbitrap Mass Spectrometry. assets.thermofisher.com/TFS-Assets/CMD/Application-Notes/AI-63770-MS-Environmental-Analysis-Compendium-AI63770-EN.pdf. Accessed 29 Oct. 2022.


" Isotopes and Mass Spectrometry (Article).” Khan Academy, www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:atomic-structure-and-properties/x2eef969c74e0d802:mass-spectrometry-of-elements/a/isotopes-and-mass-spectrometry. Accessed 30 Oct. 2022.


Libretexts. “Applications of Photoelectron Spectroscopy.” Chemistry LibreTexts, 16 Apr. 2022, chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Photoelectron_Spectroscopy/Applications_of_Photoelectron_Spectroscopy.


Photoelectron Spectroscopy - AP Chemistry. www.varsitytutors.com/ap_chemistry-help/photoelectron-spectroscopy. Accessed 29 Oct. 2022.


“Photoelectron Spectroscopy (Article).” Khan Academy, www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:atomic-structure-and-properties/x2eef969c74e0d802:photoelectron-spectroscopy/a/photoelectron-spectroscopy. Accessed 29 Oct. 2022.

33 views0 comments

Recent Posts

See All

Lupus

Comments


bottom of page