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Question: In Problem 4.43you calculated the expectation value ofrsin the stateψ321. Check your answer for the special cases s = 0(trivial), s = -1(Equation 6.55), s = -2(Equation 6.56), and s = -3(Equation 6.64). Comment on the case s = -7.

Short Answer

Expert verified

for:s=0:1s=-1:19as=-2:1135a2s=-3:1405a3

s = -7 Or smaller that the result will be undefined due to

negative numbers! = Undefined quantity

Step by step solution

01

Given information:

Equation 6.55, 6.56, 6.64 are

1r=1n2a1r2=1(l+1/2)n3a21r3=1l(l+1/2)l+1n3a3

Problem 4.43-(a) Construct the spatial wave function ψfor hydrogen in the state n = 3 , l=2 . m = 1 Express your answer as a function of r,θ,ϕ, and a (the Bohr radius) only - no other variables, (p,z etc.) or ,functions, ( y , v etc.), or constants, (A,c0etc.), or derivatives, allowed ( πis okay, and e, and 2 , etc.).

(b) Check that this wave function is properly normalized, by carrying out the appropriate integrals over r,θ,and ϕ.

(c) Find the expectation value of rsin this state. For what range of s (positive and negative) is the result finite?

02

Step 2:Check for trivial or non-trivial solution

For n = 3,l = 2,m = 1

Then:

- For s = 0:

1=6!6!1……….[Trivial]

- For s = -1

1r=5!6!3a2-1=1623a=133a=1n2a

- For s = -2:

1r2=4!6!3a22=13023a2=2135a2=12+1233a2=11+12n3a2

03

solve further

-For s = -3

1r3=3!6!3a2-3=1120827a3=122+122+133a3=1ll+12l+1n3a3

- For s = -7

1r7=-1!6!3a2-7-1!

undentified

Then for s = -7 or smaller that the result will be undefined due to

negative numbers! = Undefined quantity

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Most popular questions from this chapter

Consider the isotropic three-dimensional harmonic oscillator (Problem 4.38). Discuss the effect (in first order) of the perturbation H'=λx2yz

(for some constant λ) on

(a) the ground state

(b) the (triply degenerate) first excited state. Hint: Use the answers to Problems 2.12and 3.33

Question: Sometimes it is possible to solve Equation 6.10 directly, without having to expand in terms of the unperturbed wave functions (Equation 6.11). Here are two particularly nice examples.

(a) Stark effect in the ground state of hydrogen.

(i) Find the first-order correction to the ground state of hydrogen in the presence of a uniform external electric fieldEext (the Stark effect-see Problem 6.36). Hint: Try a solution of the form

(A+Br+Cr2)e-r/acosθ

your problem is to find the constants , and C that solve Equation 6.10.

(ii) Use Equation to determine the second-order correction to the ground state energy (the first-order correction is zero, as you found in Problem 6.36(a)). Answer:-m(3a2eEext/2)2 .

(b) If the proton had an electric dipole moment p the potential energy of the electron in hydrogen would be perturbed in the amount

H'=-epcosθ4π̀o0r2

(i) Solve Equation 6.10 for the first-order correction to the ground state wave function.

(ii) Show that the total electric dipole moment of the atom is (surprisingly) zero, to this order.

(iii) Use Equation 6.14 to determine the second-order correction to the ground state energy. What is the first-order correction?

Use Equation 6.59 to estimate the internal field in hydrogen, and characterize quantitatively a "strong" and "weak" Zeeman field.

Calculate the wavelength, in centimeters, of the photon emitted under a hyperfine transition in the ground state (n=1) of deuterium. Deuterium is "heavy" hydrogen, with an extra neutron in the nucleus; the proton and neutron bind together to form a deuteron, with spin 1 and magnetic moment

μdl=gde2mdSd

he deuteron g-factor is 1.71.

Consider the (eight) n=2states, |2ljmj. Find the energy of each state, under weak-field Zeeman splitting, and construct a diagram like Figure 6.11 to show how the energies evolve asBext increases. Label each line clearly, and indicate its slope.

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