Electron spin resonance (ESR) spectroscopy detects electron spin transitions in molecules containing unpaired electrons when irradiated with microwave radiation in the presence of a magnetic field. The ESR spectrum provides information about electron environments and interactions. Hyperfine splitting occurs when the electron spin interacts with nuclear spins, producing multiple peaks following Pascal's triangle. Superhyperfine splitting provides evidence of electron delocalization, appearing as overlapping multiplets. Anisotropic g-values from spin-orbit coupling depend on molecular orientation, shifting peak positions. Powder spectra show broadening from all orientations.
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Alkenes by absorption of light activated to higher energy singlet & triplet state and undergoes chemical reaction. These reactions are mainly:- 1. Cis - trans isomerization
2. Dimerization
3. Cycloaddition
A carbene is any neutral carbon species which contains a non-bonding valance pair of electrons.
Contributed by Alison Brown & Nathan Buehler, Undergraduates, University of Utah
Crown ethers
NOMENCLATURE
GENERAL SYNTHESIS OF CROWN ETHER
AZA CROWN
CRYPTAND
APPLICATIONS
1. SYNTHETIC APPLICTION
Esterification
Saponification
Anhydride formation
Potassium permanganate oxidation
Aromatic substitution reactions
Elimination reactions
Displacement reaction
Generation of carbenes
Superoxide anion
Alkylations – 1. o-alkylations
2. c-alkylations
3. n-alkylations
2. ANALYTICAL APPLICATION
Determination of gold in geological samples
Super critical fluid extraction of trace metal from solid and liquid materials
Application of ionic liquids in analytical chemistry
Oxidation and determination of aldehydes
Crown ethers are used in the laboratory as phase transfer catalyst
OTHER APPLICATION
It is used in photocynation
Resolution of racemic mixture
Benzoin condensation
Hetrocyclisation
Synthesis of furanones
Acetylation of secondary amines in presence of primary amine
Electron Spin Resonance (ESR) SpectroscopyHaris Saleem
Electron Spin Resonance Spectroscopy
Also called EPR Spectroscopy
Electron Paramagnetic Resonance Spectroscopy
Non-destructive technique
Applications
Extensively used in transition metal complexes
Deviated geometries in crystals
Alkenes by absorption of light activated to higher energy singlet & triplet state and undergoes chemical reaction. These reactions are mainly:- 1. Cis - trans isomerization
2. Dimerization
3. Cycloaddition
A carbene is any neutral carbon species which contains a non-bonding valance pair of electrons.
Contributed by Alison Brown & Nathan Buehler, Undergraduates, University of Utah
Crown ethers
NOMENCLATURE
GENERAL SYNTHESIS OF CROWN ETHER
AZA CROWN
CRYPTAND
APPLICATIONS
1. SYNTHETIC APPLICTION
Esterification
Saponification
Anhydride formation
Potassium permanganate oxidation
Aromatic substitution reactions
Elimination reactions
Displacement reaction
Generation of carbenes
Superoxide anion
Alkylations – 1. o-alkylations
2. c-alkylations
3. n-alkylations
2. ANALYTICAL APPLICATION
Determination of gold in geological samples
Super critical fluid extraction of trace metal from solid and liquid materials
Application of ionic liquids in analytical chemistry
Oxidation and determination of aldehydes
Crown ethers are used in the laboratory as phase transfer catalyst
OTHER APPLICATION
It is used in photocynation
Resolution of racemic mixture
Benzoin condensation
Hetrocyclisation
Synthesis of furanones
Acetylation of secondary amines in presence of primary amine
Electron Spin Resonance (ESR) SpectroscopyHaris Saleem
Electron Spin Resonance Spectroscopy
Also called EPR Spectroscopy
Electron Paramagnetic Resonance Spectroscopy
Non-destructive technique
Applications
Extensively used in transition metal complexes
Deviated geometries in crystals
NMR SPECTROSCOPY ,Relaxation,longitudinal / spin- spin relaxation,transverse / spin- spin relaxation,Shielding of proton ,Deshielding of proton,CHEMICAL SHIFT,Factors Influencing Chemical Shift,Inductive effect, Vander Waal’s deshielding,Anisotropic effect (space effect),Hydrogen bonding
,SPLITTING OF THE SIGNALS,COUPLING CONSTANT,NMR SIGNAL IN VARIOUS COMPOUND
STRUCTURE OF ATOM
Sub atomic Particles
Atomic Models
Atomic spectrum of hydrogen atom:
Photoelectric effect
Planck’s quantum theory
Heisenberg’s uncertainty principle
Quantum Numbers
Rules for filling of electrons in various orbitals
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
3. Principles of EMR spectroscopy
B 0
DE
hn
Classical theory:
Electron spin moment interacts with
applied electromagnetic radiation
m s = —
1
2
m s = —
1
2
-
Energy
Quantum theory:
transitions between energy levels
induced by magnetic field
Resonance condition
hn = gmBB0
4.
5. The EPR experiment
• Put sample into
experimental
magnetic field (B)
• Irradiate
(microwave
frequencies)
• Measure
absorbance of
radiation as f(B) Weil, Bolton, and Wertz, 1994, “Electron Paramagnetic Resonance”
6. The hyperfine effect
• The magnetic field experienced by the unpaired electron
is affected by nearby nuclei with non-zero nuclear spin
Weil, Bolton, and Wertz, 1994, “Electron Paramagnetic Resonance”, New York: Wiley Interscience.
7. Hyperfine splitting of EPR spectra
• The magnitude of the splitting and the
number of lines depend upon:
– The nuclear spin of the interacting nucleus
• # of lines = 2n(I + ½) so I = ½ gives 2 lines, etc.
– The nuclear gyromagnetic ratio
– The magnitude of the interaction between the
electronic spin and the nuclear spin
• Magnitude of the splitting typically decreases
greatly with increasing numbers of bonds between
the nucleus and unpaired electron
8. 10 Gauss
No hyperfine
1H)
14N)
2 identical I=1/2 nuclei
1 I=5/2 nucleus (17O)
Hyperfine coupling
If the electron is surrounded by n spin-
active nuclei with a spin quantum
number of I, then a (2nI+1) line pattern
will be observed in a similar way to
NMR.
In the case of the hydrogen atom (I= ½),
this would be 2(1)(½) + 1 = 2 lines.
9. Some nuclei with spins
Element Isotope Nuclear No of %
spin lines abundance
Hydrogen 1H ½ 2 99.985
Nitrogen 14N 1 3 99.63
15N ½ 2 0.37
Vanadium 51V 7/2 8 99.76
Manganese 55Mn 5/2 6 100
Iron 57Fe ½ 2 2.19
Cobalt 59Co 7/2 8 100
Nickel 61Ni 3/2 4 1.134
Copper 63Cu 3/2 4 69.1
65Cu 3/2 4 30.9
Molybdenum 95Mo 5/2 6 15.7
97Mo 5/2 6 9.46
10. Hyperfine splittings multiply with
the number of nuclear spins
O
.
O-
H
H
H
H
Benzoquinone anion radical:
1 proton – splits into 2 lines 1:1
2 protons split into 3 lines 1:2:1
3 protons split into 4 lines 1:3:3:1
4 protons split into 5 lines 1:4:6:4:1
-60 C
20 C
At higher temperature:
faster motion - sharper lines
shorter lifetime - smaller signal
13. Prushan Example
SS
N N
OO
B
FF
Cu
[Cu(Thyclops)]+
+
77 K Cryogenic ESR Spectrum of [Cu(Thyclops)]ClO4 in MeOH
Prushan, M. J.; Addison, A. W.; Butcher, R. J.; Thompson, L. K. “Copper(II) Complex Tetradentate Thioether-Oxime Ligands” Inorganica Chimica
Acta, 358, 3449-3456 (2005).
16. If the odd, unpaired electron is associated with a nucleus with nuclear
spin, can get coupling between the two spins and observe 2I+1 (I =
nuclear spin) “peaks” or “valleys”.
Examples:
di-t-butyl nitroxide radical; I(N) = 1;
Hyperfine Splitting
19. superhyperfine splitting
carbon compound; I(C) = 0; 2(0) + 1 = 1 peak…. But:
If the odd, unpaired electron spends time around multiple sets of equivalent
nuclei, additional splitting is observed: 2nI + 1; this is called “superhyperfine
splitting.”
Examples:
Triplet Quartet Pentet
21. It is possible for the unpaired electron to spend differing amounts of time on
different nuclei.
The greater the covalency, the greater is the hyperfine splitting.
Triplet: hyperfine splitting.
Doublet: superhyperfine splitting.
Interpretation: electron is spending most of
its time on CH2 protons, but spending
some time on –OH.
Pentet: hyperfine splitting.
Pentet: superhyperfine splitting.
Interpretation: electron is spending
most of its time on one set of protons,
but spending some time on other set.
22. Septet: hyperfine splitting.
IF= ½, so 2(6)(1/2) + 1 =7
Triplet: superhyperfine splitting.IN= 1, so
2(1)(1) + 1 = 3
So, spending most time on F’s, less on N.
Nonet: hyperfine splitting.
IN= 1, so 2(4)(1) + 1 =9
Pentet: superhyperfine splitting.
IH= 1/2, so 2(4)(1/2) + 1 = 5
So, spending most time on N’s, less on H.
24. High-field high-frequency EPR
X-band Q-band W-band D-band
0.33 1.25 3.5 4.9 Tesla
Bo
Microwave frequency
Superhyperfine interactions become more pronounced!
25. Anisotropic Interactions: The g-tensor
The free electron has a g-value of ge=2.0023
There may be spin-orbit coupling which will effect the ge
lets look at the simple case of Boron, 2p1.
If all the orbitals have same energy then the spin orbit coupling energy
averages to zero over the x,y, and z coordinate.
However, if the atom is placed in a crystal which removes the degeneracy then
the spin orbit coupling becomes asymmetric, px = py but do not equal to pz
Now the observed g-value will depend
upon orientation of the crystal in the
magnetic field.
26. Axial symmetry
g|| = gz and g = gx = gy
The g value tells you how strong the electron magnetic tensor is in a given
direction.
Therefore if you orientate the crystal in a different direction the energy to
resonate changes and thus the absorption will shift.
This effect is similar to shielding in the NMR experiment.
The spin-orbit coupling gives a g < g || = ge
B
gz
gy
gx B B BB
B B BB
BBBB
BBBB
g ||
g ||
g
g
|||| Hgh n
||
||
H
h
g
n
H
h
g
n
What happens if the crystal is ground into a
powder?
All orientations are present however there are more
chances that the g will be aligned with the field than g ||.
Bo
Bo
z
z
27. ESR spectra of [Cu(MeTtoxBF2)]BF4 in
1:10 BuOH–DMF.
(a) Room temperature (295 K) fluid
spectrum (9.464 GHz). (b) 77 K cryogenic
glass spectrum (9.147 GHz).
Prushan, M. J.; Addison, A. W.*; Butcher, R. J.; "Pentadentate
Thioether Oxime Macrocyclic and Quasi-Macrocyclic Complexes of
Copper(II) and Nickel(II)" Inorganica Chimica Acta, 300-302, 992-1003
(2000).