The document provides an overview of electromagnetic radiation (EMR) and its various regions, including radio waves, microwaves, infrared, visible light, ultraviolet, and X-rays. It describes the instruments used in spectroscopy, including various light sources and detectors, as well as the materials for cell construction. Additionally, it outlines Beer’s Law and Lambert’s Law regarding light absorption in relation to the concentration of solutes and the path length.

1. GENERAL
SPECTROSCOPY
EMR (ELECTRO- MAGNETIC RADIATION):- Electromagnetic waves
or EM waves are waves that are created as a result of vibrations between
an electric field and a magnetic field.
ν = c/ʎ
v =frequency, ʎ=wavelength, C=velocity of light
ΔE = hv
E =energy, h =planck’s constant,

2. Different region of EMR
Radiation

3. Electromagnetic spectrum
• Radio wave = 3-300m
• Micro wave = 1-100mm
• Ir = 2.5microm -25 nm
• Visible = 400-780nm
• UV = 200-400nm
• X-ray = 1-10nm

4. Spectroscopic technique

5. Instrument used in EMR
• Source of light
• Argon lamp(100-180)
• H2 /D2 lamp(180-380)
• Mercury arc (180-380)
• Xenon lamp (150-780)
• Carbon arc(389-789)
• Hollow cathode lamp(230-780)
• Tungsten (300-3000)
• Nerst glower(300-20000)
• Nichroma wire(800-30000)
• Laser (180-3000)uv

6. Detector
• Photon
• Thermal
• Photographic plate
• Photoconductor
• Photomultiplier
• Thermocouple
• Phototube
• Golaycell
• Silicon oxide
• Charge transfer detector
• Pyroelectric cell

7. Cell material
• Fused silica/quarz-180nm-2.5microm(Uvnear IR)
• Corex/silicate glass-230nm-2.5microm(uv near ir)
• NACL:2.5microm-25 microm (MID IR)
• KBR:over entire spectrum
• Zn,Se:1microm-50microm(Near mid far IR)

8. Law of light absorption
• Beer’s law:- relates the absorption to the concentration of
absorbing solute---intensity of light decreases exponentially with
increase in conc.
• Lambert’s law :- relates total absorption to path length ----the rate
of intensity with thickness of medium is directly prop. To intensity
of light .