UV Spectroscopy

Question 1

What is UV-visible spectroscopy?

Answer 1

A technique for analysing the absorption of UV or visible light by molecules, causing excitation of electrons

Question 2

What order does UV-vis absorption excite electrons in ?

Answer 2

From HOMO to LOMO
Highest occupied molecular orbital

Question 3

What do * and n denote ?

Answer 3

• is anti-binding
  n is non binding

Question 4

What is emission ?

Answer 4

When an electron transitions from a higher energy state to a lower energy state

Question 5

What are the applications of UV-vis spec ?

Answer 5

1. Quantitative measurements of coloured and fluorescent substances
2. Tagging of targets. Eg. DNA sequencing
3. Histo chemistry and imaging

Question 6

What are chromophores ?

Answer 6

Structural units absorbing light

Question 7

What are auxochromomes ?

Answer 7

Modify intensity or wavelength of absorption

Question 8

What is a hypsochromic shift ?

Answer 8

To shorter wavelengths (blue shift)

Question 9

What is bathochromic shift ?

Answer 9

To longer wavelength (red shift)

Question 10

What is hypchromic shift ?

Answer 10

Decreased intensity

Question 11

What is hyperchromic shift ?

Answer 11

Increased intensity