X-ray diffraction is a technique used to determine the atomic structure of crystals. When X-rays hit the periodic lattice of atoms in a crystal, the X-rays diffract into specific directions. This was first discovered by Max von Laue in 1912. Bragg's law quantifies the conditions under which constructive interference, and therefore diffraction, occurs for waves scattered by atomic planes in a crystal. X-ray diffraction methods are now commonly used to analyze crystal structures.
NQR - DEFINITION - ELECTRIC FIELD GRADIENT - NUCLEAR QUADRUPOLE MOMENT - NUCLEAR QUADRUPOLE COUPLING CONSTANT - PRINCIPLE OF NQR - ENERGY OF INTERACTION - SELECTION RULE - FREQUENCY OF TRANSITION - APPLICATIONS
A ppt compiled by Yaseen Aziz Wani pursuing M.Sc Chemistry at University of Kashmir, J&K, India and Naveed Bashir Dar, a student of electrical engg. at NIT Srinagar.
Warm regards to Munnazir Bashir also for providing us with refreshing tea while we were compiling ppt.
NQR - DEFINITION - ELECTRIC FIELD GRADIENT - NUCLEAR QUADRUPOLE MOMENT - NUCLEAR QUADRUPOLE COUPLING CONSTANT - PRINCIPLE OF NQR - ENERGY OF INTERACTION - SELECTION RULE - FREQUENCY OF TRANSITION - APPLICATIONS
A ppt compiled by Yaseen Aziz Wani pursuing M.Sc Chemistry at University of Kashmir, J&K, India and Naveed Bashir Dar, a student of electrical engg. at NIT Srinagar.
Warm regards to Munnazir Bashir also for providing us with refreshing tea while we were compiling ppt.
It contains the basic principle of Mossbauer Spectroscopy.
Recoil energy, Dopler shift.
The instrumentation of Mossbauer Spectroscopy.
Hyperfine interactions.
For UG students of All Engineering Branches (Mechanical Engg., Chemical Engg., Instrumentation Engg., Food Technology) and PG students of Chemistry, Physics, Biochemistry, Pharmacy
The link of the video lecture at YouTube is
https://www.youtube.com/watch?v=t3QDG8ZIX-8
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
It contains the basic principle of Mossbauer Spectroscopy.
Recoil energy, Dopler shift.
The instrumentation of Mossbauer Spectroscopy.
Hyperfine interactions.
For UG students of All Engineering Branches (Mechanical Engg., Chemical Engg., Instrumentation Engg., Food Technology) and PG students of Chemistry, Physics, Biochemistry, Pharmacy
The link of the video lecture at YouTube is
https://www.youtube.com/watch?v=t3QDG8ZIX-8
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
The crystal structure notes gives the basic understanding about the different structures crystalline materials and their properties and physics of crystals. It also throw light on the basics of crystal diffraction
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.
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.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Richard's entangled aventures in wonderlandRichard 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.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Mammalian Pineal Body Structure and Also Functions
X ray diffraction for m.sc. chemistry
1. Theory of X-Ray Diffraction
Shyam sunder pandiya
M.sc.chemistry
Sem.-1
M.L.V.GOVT.COLLEGE.bhiwara
2. Contents
• Introduction to X-Rays
• Crystal Structures:
Introduction to Lattices
Different types of lattices
Index Planes
• X-Ray Diffraction:
Diffraction
Bragg’s law
Diffraction Methods
3. Introduction to X-Rays
• X-rays were discovered by the German Physicist Rontgen
- he found that unlike ordinary light x-rays were invisible,
but they traveled in straight lines and affected photographic
film in the same way as light.
• X-rays are also more penetrating then light and could easily pass
through the human body, wood, thick pieces of metal, and other opaque
objects - an immediate application of this was the radiograph used by
the physicians.
• In 1912 the exact nature of x-rays was established and in the same year
the phenomenon of x-ray diffraction by crystals was discovered. This
discovery provided a new method for investigating the fine structure of
matter.
4. More Facts about X-Rays
• We now know that X-rays are electromagnetic radiation of exactly
the same nature as light but of very shorter wavelength (10-10 m = 1
Angstrom). So X-rays are ideal to probe interatomic distances which
are typically of that order.
• Typical energy scale = hc/λ = 12.3 KeV which is the characteristic
energy of x-rays.
How do you get X-rays?
How does the X-ray spectrum look like?
5. X-rays are high-energy photons that
are produced when electrons make
transitions from one atomic orbit to
another.
These transitions can be generated via
the photoelectric effect as shown. If
you send a photon into an atom with
an energy greater than the binding
energy of an electron in that atom, the
photon can knock that electron out of
its orbit, leaving a hole (or vacancy).
This hole can then be filled by
another electron in the atom, giving
off an x-ray in the transition to
conserve energy. This process is
known as fluorescence.
Many different atomic electrons of
different binding energies can fill this
hole, so you would expect to see
many energy peaks in an x-ray
spectrum.
6. Electron transitions to the K
shell of an atom are called K
X-rays, and transitions to the
L shell are called L X-rays.
Not only are energy levels
labeled, but specific atomic
transitions are labeled also.
Some of these labels are
displayed in the Figure.
The Kα1 x-ray is emitted in a
transition from the n = 2, j =
3/2 level to the K-shell; the
Kα2 x-ray is emitted in a
transition from the n = 2, j =
1/2 level to the K-shell.
The K’β1 transition is a
combination of all the
transitions from the M shell to
the K shell and the K’β2
transition is a combination of
all the transitions from the N
shell to the K shell.
7. An X-ray spectrum of erbium (Z = 68) showing both K and L x-
rays. Notice that the L x-rays have lower energy than the K x-rays
due to the fact that the allowed electron levels of an atom get closer
together in energy as n increases.
9. • A crystal may be defined as a solid
composed of atoms, ions or
molecules arranged in a pattern
periodic in three dimensions.
• Many solids are crystalline - single
crystals or polycrystalline.
• Not all solids are crystalline, however;
some are amorphous, like glass, and
do not have any regular interior
arrangement of atoms, ions, or
molecules.
• Ignoring the actual atoms, ions, or
molecules we will focus on the
geometry of periodic arrays - the
crystal is then represented as a lattice,
i.e. a three dimensional array of points
(lattice points) each of which has
identical surroundings.
NaCl Structure
CsCl Structure
10. • Two distinct concepts
in crystallography:
Lattice: consists of
points in geometrical
arrays,
Basis: describes the
arrangement of atoms
associated with each
lattice point.
Crystal Structure
= Lattice + Basis
11. Bravais Lattice
(Two equivalent descriptions)
(a) It is an infinite array of discrete
points with an arrangement and
orientation that appears exactly the
same, from whichever of the points
the array is viewed.
(b) A 3D Bravais lattice consists of
all points with position vectors R
of the form R = p a + q b + r c,
where p, q, r are integers and
(a,b,c) are any 3 vectors.
12. More examples
Simple Cubic Lattice (SC):
A choice of primitive vectors are the
three orthogonal vectors
(a x, a y, a z).
(Note: x, y, z are unit vectors)
Body Centered Cubic (BCC):
A set of primitive vectors are:
a = a x,
b = a y,
c = a/2 (x + y + z).
13. Face Centered Cubic (FCC) Lattice
A more symmetric set of
primitive vectors for the BCC
lattice is
a = a/2 (y + z ),
b = a/2 (z + x),
c = a/2 (x + y).
14. Coordination Number
The points in a Bravais lattice that are closest to a given point are
called its nearest neighbors.
Because of the periodic nature of the Bravais lattice, each point has
the same number of nearest neighbors. This number is thus a property
of the lattice, and is referred to as the coordination number of the
lattice.
Coordination numbers for
SC: 6 ( 2 x 3 )
BCC: 8 ( 2 x 4 )
FCC: 12 ( 2 x 6)
15.
16. Primitive Unit Cell
• The parallelepiped defined by the
primitive vectors (a, b, c) is
called a primitive cell or a unit
cell.
• A cell will fill all space by the
repetition of suitable crystal
translation operations.
• A primitive cell is a minimum
volume cell and there are many
ways of choosing the primitive
axes and primitive cell for a
given lattice.
19. • In 2D there are infinite number of
possibilities.
• A general lattice is the oblique
lattice and is invariant only under
rotation of π and 2π about any
lattice point.
• There are 4 special lattice type:
Square lattice, Rectangular
lattice, Hexagonal lattice, and
Centered rectangular lattice.
• So, there are 5 distinct types of
lattices in 2D.
Oblique Lattice
25. Miller Indices
• The orientation of a crystal plane is
determined by 3 points in the
plane, provided they are not
collinear.
Rules:
• Find the intercept on the axes in
terms of the lattice constants a, b,
c. The axes may be those of a
primitive or nonprimitive cell.
• Take the reciprocals of these
numbers and then reduce to 3
integers having the same ratio,
usually the smallest 3 integers. The
result, (h k l), is called the index of
a plane.
• h, k, l are known as Miller
Indices.
This plane intercepts the a, b, c
axes at 3a, 2b, 2c. The reciprocals of
these numbers are 1/3, 1/2, 1/2. So
indices of the plane are (2 3 3).
27. Spacing between Crystal planes
• It can be shown geometrically that the spacing d between
planes of Miller indices {h k l} (curly brackets imply
both +/- choices) in the cubic system is
d = a / (h2 + k2 + l2)1/2.
where a is the length of the edge of the cubic unit cell.
29. Sodium Chloride Structure
• FCC lattice structure.
• The basis consists of one Na atom
(green) and one Cl atom (blue)
separated by one-half the body
diagonal of a unit cube.
• There are 4 units of NaCl in each
unit cube, with atoms in the
positions
Cl: 000; ½ ½ 0; ½ 0 ½; 0 ½ ½;
Na:½ ½ ½; 00 ½; 0 ½ 0; ½0 0.
• Each atom has as nearest neighbors
6 atoms of opposite kind.
• Similar structures are LiH, MgO,
MnO etc.
31. Cesium Chloride Structure
• BCC lattice structure.
• One molecule per primitive cell,
with atoms at the corners 000
and body-centered positions
½ ½ ½ of the simple cubic space
lattice.
• Coordination number is 8.
• Similar structures are BeCu,
AlNi, CuZn, CuPd, AgMg etc.
33. Simplest close-packing structures
• ABABAB repeat gives Hexagonal Close-Packing (HCP)
Unit cell showing the full symmetry of the arrangement is
Hexagonal
Hexagonal: a = b, c = 1.63a, α = β = 90°, γ = 120°
2 atoms in the unit cell: (0, 0, 0) ; (2/3, 1/3, 1/2)
• ABCABC repeat gives Cubic Close-Packing (CCP)
Unit cell showing the full symmetry of the arrangement is
Face-Centred Cubic
Cubic: a = b =c, α = β = γ = 90°
4 atoms in the unit cell: (0, 0, 0); (0, 1/2, 1/2) ; (1/2, 0, 1/2);
(1/2, 1/2, 0)
36. The most common close-packed structures are METALS
A NON-CLOSE-PACKED structure adopted by some metals is:
68% of space is occupied.
Coordination Number ?
8 Nearest Neighbours at 0.87a and 6 Next-Nearest Neighbours
at 1a.
37. • Polymorphism: Some metals exist in different structure types at
ambient temperature & pressure.
• Many metals adopt different structures at different
temperature/pressure.
• Not all metals are close-packed.
39. the process by which a beam of light or
other system of waves is spread out ad
result of passing through a narrow aperture
or across an edge.
DIFFRACTION
40. the process by which a beam of light or
other system of waves is spread out ad
result of passing through a narrow aperture
or across an edge.
DIFFRACTION
41. X-rays Diffraction :-technique used to determine the
atomic and molecules structure of a crystal in which
The crystalline atom cause a beam of incident X-Ray
to Diffraction into many specific directions
Max Von Laue(1912) suggested
that X-Ray might be diffracted
while passing through a crystal
where it acts as a three
dimensional Diffraction grating
and produce interference
effect.He realized that the
wavelength of the X-Ray are
comparable to the separation of
lattice planes.
42. X-rays Diffraction :-technique used to determine the
atomic and molecules structure of a crystal in which
The crystalline atom cause a beam of incident X-Ray
to Diffraction into many specific directions
Max Von Laue(1912) suggested
that X-Ray might be diffracted
while passing through a crystal
where it acts as a three
dimensional Diffraction grating
and produce interference
effect.He realized that the
wavelength of the X-Ray are
comparable to the separation of
lattice planes.
43. Scattering of x rays by a perfect
periodic structure
Two equivalent views:
• Bragg Formulation of X-ray diffraction by a
crystal - widely used by x-ray crystallographers.
• von Laue approach - exploits the reciprocal
lattice. This approach is closer to the spirit of
modern solid state physics.
• Note: Both formulations are equivalent.
45. Bragg formulation of x-ray diffraction
by a crystal
Rays interfere
constructively if
2a = m λ
Now
a= d sin θ.
Bragg’s law of
diffraction:
2dsin θ = m λ
46. How do we perform an experiment?
• Measure angle and
intensity of radiation
as the table is
rotated.
• Apply Bragg’s law
2dsin θ = m λ
47. How do we perform an experiment?
• Measure angle and
intensity of radiation
as the table is
rotated.
• Apply Bragg’s law
2dsin θ = m λ
48. How do we perform an experiment?
• Measure angle and
intensity of radiation
as the table is
rotated.
• Apply Bragg’s law
2dsin θ = m λ
49. Laue method
A single small crystal is placed in the path of a narrow
beam of x-rays from a tungsten anticathode and the
resulting diffracted beam is allowed to fall on a
photographic plate(Laue pattern)
50. Laue method
A single small crystal is placed in the path of a narrow
beam of x-rays from a tungsten anticathode and the
resulting diffracted beam is allowed to fall on a
photographic plate(Laue pattern)
51. Powder method (debye & scherrer method
1916
A.w.hull-1917
It employs finely powdered samples in the
form of a cylinder inside a thin glass tube .
A narrow beam of x-rays is allowed in the form
of a circular arc.
52. Powder method (debye & scherrer method
1916
A.w.hull-1917
It employs finely powdered samples in the
form of a cylinder inside a thin glass tube .
A narrow beam of x-rays is allowed in the form
of a circular arc.
53. Powder method (debye & scherrer method
The scattered rays from all
sets of
Planes(eg.100,110,etc.)
In this method,no rotation is
necessary since the powered
sample . already contains
microcrystals arrenged in all
possible orientation.
Hence the large number of
them will have their Lattice
Planes in correct position for
maximum x-rays reflections
to occur.
54. Reference
-WPS OFFICE FOR ANDROID SMARTPHONE
-NOTES of Stanford university
-The elements of x-rays diffraction by stock