Podcast
Questions and Answers
What are the two types of X-rays that can be produced?
What are the two types of X-rays that can be produced?
- Thermal X-ray and Synchrotron X-ray
- Alpha X-ray and Beta X-ray
- Bremsstrahlung and Characteristic X-ray (correct)
- Hard X-ray and gamma X-ray
Why are larger atoms more likely to absorb X-ray photons?
Why are larger atoms more likely to absorb X-ray photons?
- They have a smaller atomic radius.
- They have more electrons in total.
- They emit more X-ray photons.
- Their energy levels closely match the energy of the X-ray photons. (correct)
What phenomenon describes the bending and spreading of waves when they meet an obstruction?
What phenomenon describes the bending and spreading of waves when they meet an obstruction?
- Diffraction (correct)
- Interference
- Reflection
- Refraction
In what year did Max Von Lau suggest the use of a single crystal for X-ray diffraction?
In what year did Max Von Lau suggest the use of a single crystal for X-ray diffraction?
What causes X-rays to be unable to be diffracted by ordinary optical grating?
What causes X-rays to be unable to be diffracted by ordinary optical grating?
What happens when bombarding electrons have sufficient energy during X-ray production?
What happens when bombarding electrons have sufficient energy during X-ray production?
Which of the following atomic structures is likely to produce more effective X-ray absorption?
Which of the following atomic structures is likely to produce more effective X-ray absorption?
What does Solid State Physics study in relation to X-rays?
What does Solid State Physics study in relation to X-rays?
What is a primary disadvantage of using X-rays for measurement?
What is a primary disadvantage of using X-rays for measurement?
What does a reciprocal lattice vector represent?
What does a reciprocal lattice vector represent?
Which of the following is true about the reciprocal lattice?
Which of the following is true about the reciprocal lattice?
What characteristic features correspond between a direct lattice and its reciprocal lattice?
What characteristic features correspond between a direct lattice and its reciprocal lattice?
What is one advantage of using X-rays in measurement?
What is one advantage of using X-rays in measurement?
How did P.P. Ewald contribute to the understanding of crystal structures?
How did P.P. Ewald contribute to the understanding of crystal structures?
What does the normal drawn to parallel planes in a reciprocal lattice indicate?
What does the normal drawn to parallel planes in a reciprocal lattice indicate?
Which pairing of symbols correctly represents the relationship between the direct lattice and its reciprocal lattice?
Which pairing of symbols correctly represents the relationship between the direct lattice and its reciprocal lattice?
What is the formula used to determine dhkl for a given wavelength λ and angle θ?
What is the formula used to determine dhkl for a given wavelength λ and angle θ?
What is a key advantage of using the powder method for X-ray diffraction?
What is a key advantage of using the powder method for X-ray diffraction?
In the context of the powder method, what role do crystallites play?
In the context of the powder method, what role do crystallites play?
What is the relationship between the angle of incidence and the angle of reflection in Bragg's concept of crystal reflection?
What is the relationship between the angle of incidence and the angle of reflection in Bragg's concept of crystal reflection?
What condition must be satisfied for constructive interference to occur according to Bragg's law?
What condition must be satisfied for constructive interference to occur according to Bragg's law?
During the powder method, what occurs when a monochromatic X-ray beam is incident on the powdered sample?
During the powder method, what occurs when a monochromatic X-ray beam is incident on the powdered sample?
What best describes the appearance of the diffraction lines on the film once the diffraction pattern is recorded?
What best describes the appearance of the diffraction lines on the film once the diffraction pattern is recorded?
Which formula represents Bragg's law regarding X-ray diffraction?
Which formula represents Bragg's law regarding X-ray diffraction?
What happens to X-rays when they strike a layer of a crystal?
What happens to X-rays when they strike a layer of a crystal?
What happens if a sample is not in the powdered form when using X-ray diffraction?
What happens if a sample is not in the powdered form when using X-ray diffraction?
Which statements accurately reflect the nature of crystal planes in the powder method?
Which statements accurately reflect the nature of crystal planes in the powder method?
Why can X-rays, but not visible light, be used for diffraction analysis in crystals?
Why can X-rays, but not visible light, be used for diffraction analysis in crystals?
What defines the lattice parameters in crystallography?
What defines the lattice parameters in crystallography?
What is the effective limit for the wavelength of X-rays for Bragg reflection to occur, given d ≈ $10^{-10}$ m?
What is the effective limit for the wavelength of X-rays for Bragg reflection to occur, given d ≈ $10^{-10}$ m?
In Bragg's explanation, what is meant by the term 'in-phase' concerning X-rays?
In Bragg's explanation, what is meant by the term 'in-phase' concerning X-rays?
Which statement correctly describes the path length relationship of the two X-ray beams in Bragg's model?
Which statement correctly describes the path length relationship of the two X-ray beams in Bragg's model?
What determines the reflections expected in a diffraction pattern from a crystal structure?
What determines the reflections expected in a diffraction pattern from a crystal structure?
Which of the following statements about neutron diffraction is TRUE?
Which of the following statements about neutron diffraction is TRUE?
What is a key advantage of neutron diffraction over X-ray diffraction?
What is a key advantage of neutron diffraction over X-ray diffraction?
How does the scattering mechanism of neutrons differ from that of X-rays?
How does the scattering mechanism of neutrons differ from that of X-rays?
Which of the following describes the nature of electrons used in electron diffraction?
Which of the following describes the nature of electrons used in electron diffraction?
Which type of radiation is most suitable for analyzing light elements in a crystal?
Which type of radiation is most suitable for analyzing light elements in a crystal?
What is the wavelength range of neutrons used in neutron diffraction?
What is the wavelength range of neutrons used in neutron diffraction?
What is the primary limitation of neutron diffraction?
What is the primary limitation of neutron diffraction?
Flashcards are hidden until you start studying
Study Notes
X-Ray Production
- Two types of X-rays: Bremsstrahlung (breaking radiation) and Characteristic X-rays.
- Bremsstrahlung occurs when electrons decelerate upon hitting a metal target, producing X-rays.
- Characteristic X-rays result from high-energy electrons knocking inner shell electrons from target atoms, creating vacancies filled by electrons from higher energy states, emitting photons.
X-Ray Absorption
- Larger atoms absorb X-ray photons more effectively due to greater energy differences between orbitals.
- Small atoms, like those in soft tissues, absorb X-rays poorly.
- Calcium in bones, being larger, has better absorption capabilities for X-ray photons.
X-Ray Diffraction (XRD)
- XRD involves the bending and spreading of X-ray waves when encountering an obstruction, primarily due to atomic planes in crystals.
- Max von Laue proposed using single crystals for X-ray diffraction in 1912.
- Constructive interference in X-ray diffraction occurs when reflected waves are in-phase, described by Bragg's Law: nλ = 2d sinθ, where n is the order of diffraction and d is the spacing of the planes.
Bragg's Law
- Bragg's Law stipulates that constructive interference happens when the path difference is an integral number of wavelengths.
- Valid for wavelengths approximately 10^-10 m or 1 Ã…, why visible light cannot be used for diffraction.
Powder Method
- A technique utilizing powdered samples containing numerous tiny randomly oriented crystallites.
- Provides accurate determination of lattice parameters essential for crystal structure analysis.
- Bragg's equation can be satisfied by multiple randomly oriented crystals in the sample.
Advantages and Disadvantages of X-Rays
- Advantages: X-rays are cost-effective, convenient, and minimally absorbed by air; do not require an evacuated chamber.
- Disadvantages: Limited interaction with lighter elements.
Reciprocal Lattice
- Developed by P.P. Ewald to address complexities in diffraction involving multiple parallel planes.
- Represents each set of planes with a normal vector proportional to reciprocal interplaner spacing.
- Connects directly to the direct lattice parameters, with reciprocal parameters denoting expected diffraction peaks.
Diffraction Methods
- Various methods of diffraction include X-ray, neutron, and electron diffraction, each utilizing different radiation sources.
- Mechanisms of scattering differ among the types.
Neutron Diffraction
- Neutrons have wave properties similar to X-rays but scatter primarily off nuclei due to their uncharged nature.
- Particularly effective for studying materials with light elements and magnetic ordering.
- Neutron diffraction sources are limited, making them specialized tools.
Advantages of Neutron Diffraction
- Essential for investigating magnetic ordering in materials.
- Better resolution for light atoms like hydrogen, which are less significant in X-ray patterns.
- Deep penetration into materials allows analysis of larger samples.
Electron Diffraction
- Like neutrons, electrons exhibit wave properties but interact strongly with atoms due to their charge.
- High-energy electrons may be completely absorbed by the specimen, limiting their transmission through thicker samples.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
