The electromagnetic spectrum is the complete range of electromagnetic radiation in the environment, organized by wavelength and frequency. It includes gamma rays, X-rays, ultraviolet light, visible light (which occupies a relatively small range of frequencies between infrared and ultraviolet), infrared light, microwaves, and radio waves.

Classification of the Electromagnetic Spectrum

Electromagnetic radiation (EMR) is a type of energy that exists all around us and is delivered as elementary particles called photons. Its different forms, such as visible light, microwaves, X-rays, and radio waves, are classified on the electromagnetic spectrum and are defined in terms of their wavelength and frequency.

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Contrast refers to the visible differences between the parts of a specimen. Even when a microscope has high resolution, it can be difficult to distinguish small structures because many microorganisms are relatively transparent. To improve visibility, contrast can be increased by utilizing different features of light or electrons in microscopes, or by applying dyes that bind selectively to certain structures.

Contrast

https://openstax.org/details/books/microbiology/

Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

OpenStax Microbiology Textbook

Phosphorescence is a process where a material absorbs photons and emits lower-energy photons following a delay. Because of this delayed emission, phosphorescent materials, such as those used in glow-in-the-dark plastics, can continue to emit light even after the initial energy source has been removed.

Phosphorescence

Electromagnetic Radiation (EMR)

Methods of preparation to allow us to view and distinguish different cells and their structures that were otherwise translucent through the use of ionic salts in stains/dyes. 

Staining 

Chromophores are pigments that absorb and reflect specific wavelengths of light, causing different colors to interact with them in distinct ways. In microscopy, these pigments are frequently added to specimens artificially through the use of stains, which serves to enhance the contrast and resolution of the resulting image.

Chromophores

Fluorochromes are fluorescent chromophores capable of absorbing energy from a short-wavelength excitation light source and emitting it as longer-wavelength visible light. They can be naturally fluorescent substances, like chlorophylls, or added fluorescent stains—such as Texas red, fluorescein isothiocyanate (FITC), 4',6'-diamidino-2-phenylindole (DAPI), and acridine orange—used to create contrast in fluorescence microscopy.

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