Fluorescence spectroscopy relies on:

A. the difference in color between two samples.
B. the shift in wavelength from excitation and emission.
C. the vibrations of atoms bonded together in a molecule.
D. the atomic mass of the sample the formation of specific ions.

Correct answer is b.

Explanation:

In analytical chemistry spectroscopy employs the use of spectrometers in chemical analysis.

Fluorescence spectroscopy is a type of electromagnetic spectroscopy which analyzes the fluorescence phenomenon from a sample.

It employs using a beam of light, the UV light preferably, that excites the electrons in molecules of certain compounds and causes them to emit light.

The devices that measure fluorescence phenomenon are called fluorometers.

Fluorescence however can is an emission phenomenon where an energy transition from a higher to a lower state is accompanied by radiation.

The principle has it that only molecules in their excited forms are able to emit fluorescence; thus, they have to be brought into a state of higher energy prior to the emission phenomenon.

Hence fluorescence spectroscopy relies on the shift in wavelength from excitation and emission.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).