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This article discusses the substitution structure of hydrogen atom in scattering theory and explores the phenomenon of Rayleigh scattering in clouds. It also examines the size of a hydrogen atom and estimates the lifetimes of different states. Additionally, the parallel axis theorem and its application in determining the structure of linear molecules is explained.
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P = α E Scattering Theory
H 21 cm Line Harry Kroto 2004
this shows a Hertz osci http://en.wikipedia.org/wiki/File:Dipole.gif-oli Harry Kroto 2004
Rayleigh Scattering Harry Kroto 2004
http://www.ccpo.odu.edu/~lizsmith/SEES/ozone/class/Chap_4/index.htmhttp://www.ccpo.odu.edu/~lizsmith/SEES/ozone/class/Chap_4/index.htm
Attenuation due to scattering by interstellar gas and dust clouds Harry Kroto 2004
Problems Assuming the Bohr atom theory is OK, what is the approximate size of a hydrogen atom in the n= 100 and 300 states Estimate the lifetimes of these states assuming that the ∆n = -1transitions have the highest probability.
R E = - n2 Hydrogen Atom Spectrum Harry Kroto 2004
If I is the moment of inertia of a body about an axis a through the C of G the Parallel Axis Theorem states that the moment of inertia I’ about an axis b (parallel to a) and displaced by distance d (from a) is given by the sum of I plus the product of M the total mass and the square of the distance ie Md2 a b d m1 m2 The Parallel Axis Theorem I’ = I + Md2 where M = m1 + m2
General Method of Structure Determination for Linear Molecules We wish to determine r2 the position of a particular atom (mass m2) from the Center of Mass (C of M) a b d m1 m2 I = Moment of Inertia of the normal species about a the C of M I* = Moment of Inertia of the substituted species about b its C of M I’ = Moment of Inertia of the substituted species about a
General Method of Structure Determination for Linear Molecules We wish to determine r2 the position of a particular atom (mass m2) from the Center of Mass (C of M) a is the axis of the normal molecule b is the axis of the substituted molecule a b d m1 m2 r1 r2 • For the substituted molecule the parallel axis theorem yields • I’ = I* + (M + ∆m)d2 • I’ = I +∆mr22 • I* - I = ∆mr22 – (M + ∆m) d2
I’ = I* + (M + ∆m)d2 • I’ = I +∆mr22 • I* - I = ∆mr22 – (M + ∆m) d2 I • m1r1 = m2r2 • M1(r1 + d) = (m2 + ∆m)(r2 – d) • m1r1 + m1d = m2r2 – m2d + ∆mr2 – ∆md • d(m1 + m2 + ∆m) = ∆mr2 • d = {∆m/(M + ∆m)}r2 a b d m1 m2
I* - I = {∆m - ∆m2/ (∆m + M)} r22 ∆I = μ*r22 where μ* = M∆m/(M + ∆m) The reduced mass on substituion
Problem Determine the bond lengths for the molecule H-C≡C-H H-C≡C-H B = 1.17692 cm-1 H-C≡C-D B = 0.99141 cm-1