01_XRay Intro
Page 1: Recording Notice
Session is recorded.
Class discussions will be edited before uploading to Blackboard.
Page 2: Introduction to X-ray Methods
Instructor: Dr. Duncan Parker.
Session involves various x-ray methods.
Page 3: Content Advisory
Session themes may contain sensitive topics.
Discuss concerns with the tutor beforehand or afterwards.
Support is available through University Wellbeing and Guidance teams.
Symbols indicate sensitive content in slides.
Page 4: Course Overview
Topics to cover include:
What are x-rays?
Generation methods of x-rays.
Continuous vs Characteristic x-rays.
Bragg Equation.
Structure of solids (crystals/lattices).
X-ray Diffraction (XRD) vs X-ray Fluorescence (XRF).
Page 5: Weekly Focus
Previous discussions included:
Definition and properties of x-rays within the EM spectrum.
Converting energy from Joules to electronvolts (eV).
Mapping where x-ray evidence can be analyzed.
Introduction to Bravais lattices.
Page 6: Interaction of Light and Matter
Light composed of photons.
Light treated as a wave in interactions with matter.
Electromagnetic (EM) radiation characterized by frequency and wavelength.
Page 7: Key Equations
Velocity (ms⁻¹) = frequency (s⁻¹) x wavelength (m)
Energy (kg·m²·s⁻²) = frequency (s⁻¹) x Planck’s constant (6.626 x 10⁻³⁴ kg·m²·s⁻¹)
Wavenumber (cm⁻¹) = 1 / wavelength (cm)
Page 8: Wavelength and Energy Relationship
Increasing wavelength corresponds to decreasing energy.
Overview of the electromagnetic spectrum including:
Ultra violet, X-rays, Infrared, Microwaves, and Radio.
Visible light range approximately 400-750 nm.
Page 9: X-ray Analytical Techniques
X-ray interaction involves inner shell electrons.
X-ray wavelengths range from 0.1 Å to 100 Å, equivalent to atomic-scale dimensions.
Shorter wavelengths indicate higher energy and frequency; shifts analysis from Joules to electronvolts.
Page 10: Repeat of Key Equations
Reiterates the relationships involving velocity, energy, and wavelength.
Page 11: Interaction of Light and Matter (Equations)
C = v (speed of light)
E = hv (Energy and Planck's relation)
E = hc / λ (relationship of energy with wavelength)
Page 12: Determining Energy Range of X-rays
Energy range determination in Joules using:
Planck’s constant (h = 6.626 x 10⁻³⁴ Js)
Speed of light (c = 3.0 x 10⁸ ms⁻¹)
Wavelength range considered (10⁻¹¹ m to 10⁻⁸ m).
Page 13: Converting Joules to Electronvolts (Step 1)
Calculating energy:
E = hc / λ = 1.986 x 10⁻¹⁴ J for 10⁻¹¹ m wavelength.
Page 14: Converting to Electronvolts (Step 2)
Voltage as a measure of energy:
1 V = 1 J/Coulomb; use of elementary charge for conversion.
Page 15: Finalizing Electronvolt Calculation (Step 3)
Maximum energy of X-ray:
E = 1.986 x 10⁻¹⁴ J / 1.602 x 10⁻¹⁹ C = 123970 eV (or 124 keV).
Page 16: Discussion Activity
Group discussion on the advantages of using electronvolts vs. Joules.
Page 17: Methods of X-ray Generation
Three methods for x-ray generation:
Bombardment with high-energy electrons.
Fast-moving charged particles.
Direct generation from x-rays.
Page 18: Applications of X-rays
X-rays provide elemental information about materials.
Group discussion on potential evidence types for x-ray analysis.
Page 19: Characteristics of X-ray Methods
Non-destructive analysis.
Suitable for solid or crystalline sample forms (both organic and inorganic).
Page 20: Lattice Structures
Metals and ionic molecules form repeating lattice structures.
Complicated structures arise in minerals; organic molecules also form lattices.
Additional materials on lattice structures available on Blackboard.
Page 21: Unit Cell Concept
Definition and significance of a unit cell in ionic lattices.
Repeated unit crucial in understanding lattice characterization.
Page 22: Types of Ionic Lattices
Based on four known metal structure types:
Primitive cube.
Body-centered cube.
Face-centered cube.
Hexagonal close-packed.
Page 23: Exploring Metal Structures
Beyond standard types, manipulation of metal structures leads to:
7 Crystal Systems.
14 Bravais lattices.
Page 24: Polymorphs Significance
Two crystals with the same formula but differing structures are polymorphs.
Example: Oral medicines may only be active in one polymorph.
Historical example: Vinland Map and synthetic inks.
Page 25: Cubic Crystal System
Characteristics:
3 Bravais lattices; all sides equal; 90-degree angles.
Requires 4 three-fold rotation axes.
Page 26: Hexagonal Crystal System
Features:
1 Bravais lattice; 2 equal sides, 1 longer side; two different angles.
Must have 1 six-fold rotation axis.
Page 27: Rhombohedral Crystal System
Contains:
1 Bravais lattice; all sides equal, angles equal but not 90 degrees.
Requires 1 three-fold rotation axis.
Page 28: Tetragonal Crystal System
Attributes:
2 Bravais lattices; 2 equal sides, all angles at 90 degrees.
Contains 1 four-fold rotation axis.
Page 29: Orthorhombic Crystal System
Definition:
4 Bravais lattices; no equal sides; all angles 90 degrees.
Must have multiple axes of rotation or mirror planes.
Page 30: Monoclinic Crystal System
Characteristics:
2 Bravais lattices; no equal sides; two angles at 90 degrees.
Must have a 2-fold axis or a mirror plane.
Page 31: Triclinic Crystal System
Characteristics:
1 Bravais lattice; no equal sides or angles.
No elements of symmetry.
Page 32: 3D Visualization Tool
Utilize the provided link to visualize crystal systems and their symmetry.
Future lectures will revisit lattice analysis using x-ray methods.
Page 33: Summary of Topics Covered
Reviewed key components of x-rays and their EM spectrum position.
Discussed energy conversion from joules to electronvolts.
Analyzed evidence applicable for x-ray techniques.
Introduced Bravais lattices.
Page 34: Overview of Next Week
Next week's focus:
Application of x-ray energy insights.
Exploration of x-ray generation methods.
Detailed examination of x-ray interaction with matter.