Absorption spectroscopy

Spectroscopy is…?

Spectroscopy is the examination or viewing of colour.

Purpose of spectroscopy

Qualitative/quantitative cognition of

matter and follow time scaled change of matter.

What is a spectrum

Representation of one intensity like-quantity as a function of an energy-like quantity

What is a continuous emission spectrum?

Shows a glowing hot solid from a liquid source

What is an emission line-type spectrum

Shows a hot rarefied gas at high pressure

What is absorption line-type spectrum

Absorption of a cooler gas

The concept of absorption is?

When an electron in ground state is transmitted enough energy to excite it a certain level called excited state

How does light in a material lose its intensity

When it is propagated

Lambert-Beer law?

I= I0 e- E(wavelength)cx

What does Lambert-Beer law explain?

Decrease of light intensity in dilute solutions

Absorbance is…?

Negative logarithm of light leaving the solution (I)

Absorbance formula?

A = E(wavelength)cx

On what does light absorption depend ?

Wavelength

Amino acids in majority of proteins?

Tryptophan, tyrosine and phenylalanine

How do the amino acids in the proteins affect them?

Give absorption maximum of 280nm

What gives absorption peak at 220nm?

Peptide bonds

Absorption peak of nucleic acids and what causes it?

260nm due to pyrimidine and purine bases

Formula for transmission?

T=I/IO

Function of spectrophotometer

To record absorption spectrum, it is commonly used in biochemistry to measure small materials

Parts of spectrophotometer

Light source, Monochromator, sample holder, photodetector, electronic unit, computer and mirrors

How can the spectrophotometer be arranged

Single beam(one curette) and Double beam (2 curettes)

How does light interact with matter

by reflection, absorption, transmission and scattering.

Jablonski schematic?

Electronic, vibrational, rotational transition or all three

How to return from unstable excited state to ground state?

Non radioactive transition and transition with radiation