Lecture 1: RDCH 702 Introduction • Class organization Outcomes Grading • Chart of the nuclides Description and use of chart Data • Radiochemistry introduction Atomic properties Nuclear nomenclature X-rays Types of decays Forces 1-1 RDCH 702: Introduction • Outcomes for RDCH 702 Understand chemical properties in radiation and radiochemistry Use and application of chemical kinetics and thermodynamics to evaluate radionuclide speciation Understand the influence of radiolysis on the chemistry of radioisotopes Understand and evaluate radioisotope production Evaluate and compare radiochemical separations Utilization of radioisotope nuclear properties in evaluating chemical behavior Use and explain the application of radionuclides in research Discuss and understand ongoing radiochemistry 1-2 research Grading • Homework (25 %) Weekly homework questions Develop tools for research (spreadsheets) • Two exams (30 % each) Oral exam 30 minutes each 1st exam on question from course information 2nd exam on literature • Classroom participation (15 %) Bring chart of the nuclides! • Class developed to assist and compliment research activities 1-3 Chart of the Nuclides • Presentation of data on nuclides Information on chemical element Nuclide information Spin and parity (0+ for even-even nuclides) Fission yield Stable isotope Isotopic abundance Reaction cross sections Mass • Radioactive isotope Half-life Modes of decay and energies Beta disintegration energies Isomeric states Natural decay series Reaction cross sections 1-4 Chart of Nuclides • Decay modes Alpha Beta Positron Photon Electron capture Isomeric transition Internal conversion Spontaneous fission Cluster decay 1-5 Introduction • • Radiochemistry Chemistry of the radioactive isotopes and elements Utilization of nuclear properties in evaluating and understanding chemistry Intersection of chart of the nuclides and periodic table Atom Z and N in nucleus (10-14 m) Electron interaction with nucleus basis of chemical properties (10-10 m) Electrons can be excited * Higher energy orbitals * Ionization Binding energy of electron effects ionization Isotopes Same Z different N Isobar Same A (sum of Z and N) Isotone Same N, different Z Isomer Nuclide in excited state 99mTc 1-6 X-rays • Electron from a lower level is removed electrons of the higher levels can come to occupy resulting vacancy energy is returned to the external medium as electromagnetic radiation • radiation called an X-ray discovered by Roentgen in 1895 In studying x-rays radiation emitted by uranium ores Becquerel et. al. (P. and M. Curie) discovered radioactivity in 1896 1-7 X-rays • • • • Removal of K shell electrons Electrons coming from the higher levels will emit photons while falling to this K shell series of rays (frequency n or wavelength l) are noted as Ka, Kb, Kg If the removed electrons are from the L shell, noted as La, Lb, Lg In 1913 Moseley studied these frequencies n, showing that: n A(Z Zo ) where Z is the atomic number and, A and Z0 are constants depending on the observed transition. K series, Z0 = 1, L series, Z0 = 7.4. Lg Lb O N M Kb La Ka L K (a) l j E(keV) 2 2 1 1 0 5/2 3/2 3/2 1/2 1/2 0,077 0,079 0,151 0,164 0,231 2 2 1 1 0 5/2 3/2 3/2 1/2 1/2 0,728 0,741 0,990 1,056 1,215 1 1 0 3/2 1/2 1/2 5,014 5,360 5,706 0 1/2 35,974 (b) Lg1 Lb4 Lb3 Lb2 Lb1 valeurs de l(A;° ) 2,34723 2,66587 2,63521 2,51146 2,68321 valeurs de l(A;° ) 2,90145 La2 2,89193 La1 2,98932 L Ll 3,26618 0,34608 Kb2 valeurs de l( A;° ) 0,35434 Kb1 0,40482 Ka2 0,40026 Ka1 1-8 1-9 Absorption Spectra • Edge keV A • K 115.6061 0.1072 • L-I 21.7574 0.5698 • L-II 20.9476 0.5919 • L-III 17.1663 0.7223 • M1 5.5480 2.2348 • M2 5.1822 2.3925 • M3 4.3034 2.8811 • M4 3.7276 3.3261 • M5 3.5517 3.4908 • N1 1.4408 8.6052 • N2 1.2726 9.7426 • N3 1.0449 11.8657 U absorption edges and scattering coefficients 1-10 Fundamentals of x-rays • X-rays X-ray wavelengths from 1E-5 angstrom to 100 angstrom De-acceleration of high energy electrons Electron transitions from inner orbitals * Bombardment of metal with high energy electrons * Secondary x-ray fluorescence by primary x-rays * Radioactive sources * Synchrotron sources 1-11 Types of Decay 1. a decay (occurs among the heavier elements) 226 88 Ra Rn a Energy 222 86 4 2 2. b decay I Xe b n Energy 131 53 131 54 3. Positron emission 22 11 Na Ne b n Energy 22 10 4. Electron capture 26 13 Al b Mg n Energy 26 12 5. Spontaneous fission Cf Xe Ru 4 n Energy 252 98 140 54 108 44 1 0 1-12 Half Lives for the condition: N/No=1/2=e-lt N=Noe- lt l=(ln 2)/t1/2 Rate of decay of 131I as a function of time. http://genchem.chem.wisc.edu/sstutorial/FunChem.htm 1-13 Forces in nature • Four fundamental forces in nature All interactions in the universe are the result of these forces • Gravity Weakest force most significant when the interacting objects are massive, such as planets, stars, etc. • Weak interaction Beta decay • Electromagnetic force Most observable interactions • Strong interaction Nuclear properties 1-14 Fundamental Forces 1-15 Classic and relativistic 1-16 Use of relativistic terms • • • • relativistic expressions photons, neutrinos Electrons > 50 keV nucleons when the kinetic energy/nucleon exceeds 100 MeV 1-17 Wavelengths and energy • Planck evaluated minimum from DExDt when he studied the radiation emitted by a black body at a given temperature • Quantum called Planck’s constant h (h = 6.6 10-34 J.s). radiation conveys energy E in the form of quanta E = hn n the frequency of the emitted radiation • Based on the wave mechanics worked out by de Broglie l = h/p l is the wavelength associated with any moving particle with the momentum p /p h 2 1-18 Wavelengths • Photon relationships 1-19 Particle Physics • fundamental particles of nature and interaction symmetries • Particles classified as fermions or bosons Fermions obey the Pauli principle antisymmetric wave functions half-integer spins * Neutrons, protons and electrons Bosons do not obey Pauli principle * symmetric wave functions and integer spins Photons 1-20 1-21 Particle physics • Particle groups divided leptons (electron) hadrons (neutron and proton) hadrons can interact via the strong interaction Both can interact with other forces Fermionic Hadrons comprised of quarks 1-22