Spectroscopy Flashcards
What is spectroscopy?
Study of interaction of electromagnetic waves with matter
What is the application of spectroscopy?
Quantitative estimation
Kinetics of reaction
Structure determination
Identification of unknown solute
Name the techniques for the following electromagnetic radiation
X Rays
UV
Visible
IR
Microwave
Radiowave
X rays crystallography
UV Vis Spectroscopy
IR spectroscopy
Microwave spectroscopy
Electron spin reversal spectroscopy and NMR
Two types of spectroscopy?
Absorption and emission spectroscopy
Beer Lamberts Law
Absorbance is directly proportional to solute concentration and path length of the light travelled.
What is the unit of absorbance?
Unit less
What is the unit of molar extinction coefficient?
M-¹ cm-¹
Formula of absorbance?
A = log10 l°/l
A = log 10 1/T
A = 2 - log10 (%T)
What is the application of colorimetre?
Quantitative estimation
What is the range of far UV absorption and near UV absorption?
Far - 190 to 250
Near - 250 to 280
When does DNA or RNA and peptide bonds get absorbed in UV spectroscopy?
DNA and RNA - 250 nm
Peptide bonds - 210 nm
What range of UV spectroscopy does protein(tryptophan and tyrosine), phenylalanine and disulfide linkage gets absorbed?
Protein
Tryptophan - 280
Tyrosine - 270
Phenylalanine - 260
Disulphide linkage - 255
Which of the near or far UV region is impossible?
Sigma to sigma star
Pie to sigma star
What is the ratio of pure DNA 280/260
1.8
What is the ratio of pure RNA 280/260?
2.0
What contributes to intrinsic fluorescence?
Aromatic amino acid
What is the application of IR spectroscopy?
Identification of chemical composition
What is the application of circular dichroism?
Identification of secondary structure and conformational changes due to protein - protein interaction.
How many peaks will be developed in circular dicorism for the following: -
a helix
B helix
Random coil
a helix - one positive and two negative
B helix - one positive and one negative
Random coil - one strong negative and one weak positive
What is the application of NMR?
Structure determination
Functional group analysis
3D structural of biomolecule in their native state
Name two NMR active atoms.
1H, 13 C
What is stoke shift?
The difference in absorption peak and emission peak in a graph.
Name the two types of transition in emission spectroscopy.
Non radiative and radiative
What is a fluorophore?
A component that causes a molecule to absorb the energy of a specific wavelength and re-emit the energy.
Give an example of vibrational spectroscopy.
IR spectroscopy
Does IR spectroscopy induce electronic transition?
No
Name the instrument that determines the IR absorption spectrum for the compound.
Infrared spectrometer
Name the two regions in the IR spectra.
Functional group region and fingerprint region
What is the range of fingerprint region?
1200 to 700 cm-¹
Does NMR spectroscopy detect any nucleus?
No, only those nuclei which have magnetic properties.
If the number of neutrons and number of protons are even then individual spin is what and overall spend becomes what?
Individual spin is paired and overall spin becomes zero.
If the number of neutrons and number of protons are both are odd then the nucleus has what kind of spin?
Integer spin
If the number of neutrons plus the number of protons is odd then what kind of spin does nucleus have?
Half integer spin
Electrons with what kind of spin have covalent bond?
Opposite spin
Which have lower energy, positive half spin or negative half spin?
Positive half spin
NMR is detected in what?
NMR spectrometer
What is the full form of TMS?
Tetramethylsilane
Raman spectroscopy
Involves the scattering of radiation by sample
Inelastic scattering?
The light is scattered at the frequency that differ from the incident light.
Elastic scattering?
When the light is scattered at the same frequency as the incident light
What does mass spectrometry determine?
Mass of an ionic species
How does mass spectrometry determine mass?
By measuring mass to charge ratio
Name the three basic components of mass spectrometry.
Ionisation source
Mass analyser
Detector
What gives the sample charge?
Ionisation
Full form of MALDI.
Matrix assisted laser desorption/ionisation
Which matrix is commonly used in the MALDI?
Aromatic compounds
What is MALDI?
It is a type of desorption ionisation in the mass spectrometry ionisation
What happens in the ionization process of the mass spectrometry?
Conversion of solute to the gas phase and maintaining their charge.
What happens in mass analysers of the mass spectrometry?
The sample are passed into mass analyser where they are separated according to their mass to charge ratio.
Name the most common type of mass analyser.
Time of flight (TOF)
How does TOF determine the mass?
It is based on the different velocity rate of different ions. The smaller ions move faster than larger ions.
Application of mass spectrometry.
To determine the mass of an unknown compound
Determine the structure
How to determine the sequence of polypeptide?
Tandem MS or MS-MS
