chap12 - Chap 12 IR and Mass Spec Spectroscopy- help...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chap 12 IR and Mass Spec Spectroscopy- help determine the structure of organic molecules. In the past use reactions. 15 need a large sample 16 hard for complex molecules 17 destructive IR 1. IR- absorption spectroscopy- light is absorbed, a specific wavelength absorbed is measured. Based on the vibrations of bonds and provides evidence of functional groups. λ = wavelength υ = frequency c = λ x υ low energy and high energy related to wavelength. Short wavelength = high energy. ε = photon energy ε = h υ = hc/ λ h = Plank’s constant ε = matches the difference between ground state and excited state IR must have a dipole moment. IR =Cause atoms to vibrate. Microwave = rotations Radio wave = nuclear spin transitions. IR measures wave numbers = number of wave lengths in a centimeter. 1 cm = 10,000 μ m wavelength measured in μ m wavenumber (cm -1 ) = 1/ λ (cm) Assume two weights on a spring. frequency of the stretching Vibrations dependent on: 1. Mass of atoms-heavier atoms, frequency decreases λ
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 2. Strength of bond. – stronger bonds require more force so vibrate faster so frequency increases with bond strength. 3.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 9

chap12 - Chap 12 IR and Mass Spec Spectroscopy- help...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online