Optical Methods Of Chemical Analysis PDF 2024

OPTICAL METHODS OF CHEMICAL ANALYSIS Light Sample Chemical information F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024 1  OPTI...

OPTICAL METHODS OF CHEMICAL ANALYSIS Light Sample Chemical information F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024 1  OPTICAL METHODS OF CHEMICAL ANALYSIS 1 Absorption 4 Reflectance methods methods 2 Emission 3 Scattering methods methods F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024 2 1 ABSORPTION OF RADIATION INCIDENT TRANSMITTED RADIATION RADIATION (Intensity, Io) sample (Intensity, I) cell I < Io I = Io 10- l C BEER’S LAW A = log (Io / I) =  l C 3 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  NATURE OF LIGHT LIGHT WAVE PARTICLE wavelength energy frequency E = h = h c /  4 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  5 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  UV-VIS MOLECULAR SPECTROSCOPY Region Wavelength (nm) Energy (J/photon) Far ultraviolet 10-200 1.99x10-17- 9.93x10-19 Near ultraviolet 200-400 9.93x10-19- 4.96x10-19 Visible 400-800 4.96x10-19- 2.48x10-19 Very near infrared 800-1100 2.48x10-19- 1.81x10-19 Erad < Etrans  Erad > Etrans  Erad = hc / λ Erad = Etrans  Erad ? ΔEtrans 6 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  Energy Transfer through Resonance 7 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024 INTERACTION OF LIGHT AND MATTER 4p EXCITED STATE) 330 nm 3d 819 nm 3p 590 nm 3s l = 1 GROUND m = 0, 1 STATE ATOMIC ABSORPTION SPECTROMETRY MOLECULAR ABSORPTION SPECTROMETRY F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024 8 INTERACTION OF LIGHT AND MATTER v3 Electronic excited v2 state (S1) v1 Rotational v0 energy sub-levels v3 Electronic ground v2 Vibrational state (S0) v1 energy sub-levels v0 MOLECULAR ABSORPTION SPECTROMETRY F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024 9  ABSORPTION SPECTROSCOPY 4p Atomic Absorption Molecular Absorption Spectrometry 3d Spectrometry 330 nm 819 nm 3p 590 nm line spectra 3s band spectra transitions in transitions in atomic orbitals molecular orbitals 10 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  ABSORPTION SPECTROSCOPY In UV-VIS spectroscopy, Molecular Absorption only electronic transitions Spectrometry occur. NO rotational and vibrational transitions. Because of the large number of vibrational and rotational energy levels, the absorption spectra appears as continuous bands. 11 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  ABSORPTION SPECTROSCOPY Atomic Absorption Molecular Absorption Spectrometry Spectrometry Atomizer Sample LINE BAND SOURCE SOURCE Sample 12 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  MOLECULAR ABSORPTION SPECTROSCOPY UV-VIS Spectrometry Infra-red Spectrometry electronic transition vibrational transition light source: lamps light source: thermal detector: photoelectric detector: thermal cell: glass; plastic cell: inorganic salt 13 F. Sevilla III / J.H. Bergantin Jr. Methods of Analysis 2024  FT-IR spectrometers based on a Michelson interferometer with one mirror as movable to allow a variable delay to be included in one beam 14 F. Sevilla III / J.H. Bergantin Jr. Optical Methods of Analysis 2024  15 F. Sevilla III / J.H. Bergantin Jr. Optical Methods of Analysis 2024 Skoog, Holler, Crouch. Principles of Instrumental Analysis, 7th ed.  The output of the interferometer is an interferogram which stores spectral information from the sample in a time domain. F. Sevilla III / J.H. Bergantin Jr. Optical Methods of Analysis 2024 Skoog, Holler, Crouch. Principles of Instrumental Analysis, 7th ed.  FT-IR spectrometers Shimadzu IRPrestige-21 optical system F. Sevilla III / J.H. Bergantin Jr. Optical Methods of Analysis 2024 17 https://www.shimadzu.com/an/ftir/support/tips/letter1/power1.html  Fourier Transform IR spectrometers employs frequency modulation to allow multiplex scanning applies Fourier transform techniques to decode spectra measures all wavelength simultaneously; performs multiple rapid scans to improve S/N ratio (Fellgett advantage) involves greater intensity of radiation falling on the detector (Jacquinot advantage) features accurate and precise wavenumber calibration through the He-Ne laser internal standard (Connes advantage) F. Sevilla III / J.H. Bergantin Jr. Optical Methods of Analysis 2024 18