Fluorescence Anisotropies is a scientific term used in the field of fluorescence spectroscopy. It refers to the difference in fluorescence emission intensity when polarized light is used to excite a molecule. The IPA phonetic transcription of the word is [flʊɹəsəns əˌnɪsəˈtɹɑpiz]. The /fl/ sound is followed by /ʊ/ and then /ɹ/ in the first syllable. /ə/ is used for the schwa sound, and there are two syllables emphasized with a secondary stress, represented by the apostrophes. The word is spelled phonetically, so the pronunciation can be easily determined.
Fluorescence anisotropies are a set of quantitative measurements used in fluorescence spectroscopy that describe the degree of rotational motions of fluorescent molecules in a sample. It refers to the differences in the emitted light intensity depending on the orientation of the molecules with respect to the excitation light polarization.
When anisotropic molecules are excited by polarized light, their fluorescent emission will also exhibit polarization. This polarization can be described by the fluorescence anisotropy values. It provides information about the rotational freedom of the molecules and the orientation of their emitting dipoles.
Fluorescence anisotropies are calculated by comparing the intensities of emitted light parallel (I||) and perpendicular (I⊥) to the excitation light polarization. The formula for anisotropy, represented by r, is given as (I|| - G × I⊥) / (I|| + 2 × G × I⊥), where G is the instrument factor accounting for any instrumental polarization.
Fluorescence anisotropies find application in many scientific areas, including biochemistry, molecular biology, and materials science. They are used to determine the physical properties of chromophores, such as molecular size, shape, and orientation. Researchers employ fluorescence anisotropy measurements to study conformational changes in biomolecules, protein-ligand interactions, membrane fluidity, and the dynamics of macromolecules.
In summary, fluorescence anisotropies quantify the polarization of emitted light from excited molecules and provide essential insights into their rotational motions and orientations.
The term "fluorescence" refers to the emission of light by a substance after it has absorbed photons of a shorter wavelength. It comes from the Latin word "fluere", meaning "to flow".
"Anisotropy" is a term used in physics to describe the property of being directionally dependent. It comes from the Greek words "anisos", meaning "unequal", and "tropos", meaning "turn" or "direction".
When these two terms are combined, "fluorescence anisotropy" refers to a measure of the polarization of emitted light during fluorescence, indicating the degree of directional dependence of fluorescence emission.
Therefore, the etymology of the term "fluorescence anisotropies" is a combination of Latin and Greek origins, reflecting the properties being described by the term.