What does “spectroscopy” mean?
The measurement of light
What does spectroscopy measure in general?
How matter interacts with light
What type of light does UV-Vis spectroscopy measure?
Ultraviolet and visible light (approx. 200–700 nm).
How many colours can the human eye distinguish?
About 10 million.
What are additive primary colours?
Red, Green, Blue (RGB).
What are subtractive primary colours?
Cyan, Magenta, Yellow (CMY).
What does red + green light make (additive mixing)?
yellow
What does blue + yellow pigment make (subtractive mixing)?
brown
What determines which wavelengths a molecule absorbs?
electronic strucuture
What happens when a molecule absorbs light?
Electrons move to a higher energy level.
Typical wavelength range of visible light?
400–700 nm.
What is the relationship between frequency and wavelength?
speed = frequency × wavelength.
What does a monochromator do?
Selects a specific wavelength of light.
Which cuvette material allows full 200–700 nm range?
quartz
Why can’t plastic cuvettes be used for UV?
Plastic absorbs UV light.
What does a spectrophotometer actually measure?
Transmittance (T) — the light that passes through the sample.
Why don’t we measure absorbance directly?
Because detectors can only measure transmitted light, not absorbed light.
How is absorbance defined?
A=−log(T).
Does absorbance have units?
No, absorbance is unitless.
What does ε represent in Beer–Lambert Law?
Molar extinction (absorption) coefficient.
What does l represent in Beer–Lambert Law?
Path length (usually 1 cm).
What does c represent?
Concentration of the absorbing species
What absorbance range gives the best data for calibration curves?
0.1 < A < 1.
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Intro states of matter23
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Atoms upward15
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periodic table trends22
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Bonding21
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Mole Calculations, Dilutions, Ph, Conc17
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mass spectrometry22
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chromatography28
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intro to organic chemistry23
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Organic Chemistry – Alcohols, Carbonyls & Reactions30
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NMR spectroscopy24
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spectroscopy30
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infrared spectroscopy8
