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Definition
d^(2)psi -2m[E-U(x)]psi(x)
---------- = ---------------------
dx^(2) hbar^(2)
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Definition
it increases as the particle's kinetic energy decreases
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When is the de Brogile wavelength the same at all positions? |
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Definition
if U is constant then K is constant, thus the de Brogile wavelength is the same at all positions |
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What is the relationship between the de Brogile wavelength with K |
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Definition
inverse relationship...as K increases the wavelength decreases |
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When can you solve the Schrodinger equation? |
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Definition
It can't be solved until U(x) has been specified |
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Definition
The conditions or restrictions on acceptable solutions |
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Primary Conditions a Wave Function must obey:
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Definition
1. psi(x) is a continuous function
2. psi(x)=0 if x is in a region where it is physically impossible for the particle to be.
3. psi(x) --> 0 as x--> +infinity and x --> -infinity
4. psi(x) is a normalized function |
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General Solution for psi(x) |
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Definition
psi(x)= Apis1(x) + Bpsi2(x) |
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How to solve a quantum mechanics problem |
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Definition
1. Determine a pontential-energy function.
2. draw the potential energy curve
3. establish the boundary conditions that the wave function must satisfy.
4. normalize the wave functions
5.draw graphs of psi(x) and lpsi(x)l^(2)
6. determine the allowed energy levels
7. calculate probablities, wavelengths, or other quantities |
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What are the solutions to the Schrodinger equation? |
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Definition
The stationary states of the system |
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Jumping from one stationary state to another |
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Definition
deltaE lEf-Eil
f = ------- = --------
h h |
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What does a standing de Brogile wave lead to? |
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Definition
It leads to an energy quantization; only discrete energies allowed |
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Definition
a box whose walls are so strudy that they can confine a particle no matter how fast the particle moves. |
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Characteristics of a Rigid Box |
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Definition
1. The can move freely between X=0 and X=L at a constant speed; constant K.
2. No matter how much K, the turning points are at 0 and L.
3. The regions x<0 and x>L are forbidden. The particle cannot leave the box.
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Potential Energy for a Rigid Box |
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Definition
U(x)= 0 0(</=) X (</=)
U(x)= infinity X<0 or X>L |
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Definition
1. since U(x)=0 then the second derivative of psi in respect to x is -2mEpis(x)
= ------------
hbar^(2)
2. Beta^(2) 2mE
= ------
hbar^(2) |
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What functions second derivative is a negative constant times the function itself?
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Definition
psi1(x)=sin(Betax) psi2(x)=cos(Betax)
2. Then you take the second derivative of each psi and put it in the psi(x)=Apsi1(x) + Bpsi2(x)
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Definition
For x=o psi(x)=o for this condition and the B part does not fit the property. |
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Where X=L:
psi(x=L)=Asin(betaL)=0 |
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Definition
1. solve for (beta)*(L); so find a constant that helps achieve sin(betaL)=0
2. solve for beta and plug it into psi(x) |
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Definition
since Beta sqrt(2mEn) npi
= --------- = ----- n=1,2,3...
hbar L
2. solve for energy En=n^(2) h^(2)/8mL^(2)=n^(2)E1.
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Definition
1.these are the only values forE for which there are physically meanigful solutions to the Sch. equation.
2. it is the energy of the stationary state with quantum number n
3. E1 is the ground state energy |
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Definition
1. equation on reference sheet.
2. solve for An, which seems to always equal sqrt(2/L). |
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Nodes and antinodes for psi(x) |
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Definition
has (n-1) nodes and n antinodes (maxima and minima). |
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Definition
a quantum particle in a box cannot be at rest
E1 is the zero-point motion |
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Condition for having a Stationary wave |
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Definition
the de Brogile waves have to form standing waves |
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Definition
Bohr's idea that the quantum world should blend smoothly into the the classical world for high quantum numbers. |
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What is the probability of finding a classical particle within a small interval dx |
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Definition
the fraction of its time that it spends passing through dx
Probclass(in dx at x)=(dt/.5T)= (2/Tv(x)) |
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Classical Probability density |
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Definition
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Definition
1. classically forbidden regions are E<U0
2. the wave function on the graph extends into the classically forbidden area
3. there are only a finite number of bound states
4. represent electrons confined to or bound in the potential well
5.no stationary states E>U0 |
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Definition
1. because the wave functions are slightly more spread out, you get a lower velocity and thus lower energy.
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Classically Forbidden Region |
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Definition
1. e^(x/P.D.) and e^(-x/P.D.) are used where psi(x)=Ae^(x/P.D.) + Be^(-x/P.D.) for x greater than or equal to L
2. psi-->0 as x-->infinity
3. since e^(x/P.D.) diverges as x--->infinity A=0 |
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Definition
psi(at x=L)= Be^(-L/P.D.)= Psiedge
1. solve for B to get Psi(x)=Psiedge e^-((x-L)/P.D.) for X (>/=)L |
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Definition
P.D. hbar
= ---------------
sqrt(2m(U0-E)) |
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Quantum Harmonic Oscillator |
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Definition
w=sqrt(k/m)
U(x)=.5kx^(2) |
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Quantum-Mechanical Tunneling |
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Definition
1. A higher total energy line means a larger K not a higer elevation
2. tunnels its way through the hill and emerges on the other side
3. requires not expenditure of energy |
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Energy for Hydrogen ch.42 |
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Definition
En= -13.60eV/n^(2) n=1,2,3
n is the principal quantum number |
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Definition
L= sqrt(l(l+1)) hbar l=0,1,2,3..., n-1
l is the orbital quantum number |
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Z-component of the angular momentum |
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Definition
Lz= (m)(hbar) m=-l, -l +1,...,0,..., l-1, l
m is the magnetic quantum number |
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Angular Momentum is Quantized |
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Definition
thetalm=cos^(-1)(Lz/L)
ground state of l=0 has no angular momentum |
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Definition
absolute value of E1=13.60eV, is the minimum energy that would be needed to form a hydrogen ion by removing the electron from the ground state. |
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Otto Stern and Walter Gerlach |
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Definition
1. prepare an atomiv beam by evaporating atoms out of a hole in an oven
2. an atom whose magnetic moment vector mnu is tilted upward (mnu >0) has an upward force on it's north pole that is larger than the downward force on its south pole.
3. a downward tilted magnetic moment (mnu<0)experiences a net downward force
4. A magenetic moment perpendicular to the field (mnu=0) feels no net force and passes through the magenet with no deflection. |
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Definition
1. ms= (+/-)1/2
2. spin up state is the positive and spin down is the negative
3. The electron's spin is an intrinsic quantum property of the electron that has no classical counterpart |
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Definition
delta l= absolute value of l2-l1=1
lamda= (hc)/(deltaEatom) |
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Definition
Nexc=N0e^(-t/T)
where T=1/r
r is the decay rate =Prob(emission in deltat at time t)/(deltat) |
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Definition
Epulse=(Power)(deltat)
Ephoton= hf=(hc)/(lambda)
Epulse=N (Ephoton) |
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Definition
- the atoms of an element with different values of A; where A=Z+N
- only 266 are stable
- isobars- same A but different Z and N
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Definition
- r=r0A^(1/3) where r0=1.2fm
- all nuclei have the same density of 2.3 x10^(17) kg/m^(3)
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Definition
- The energy you would need to supply to a nucleus to disassemble it into individual protons and neutrons
- B=(ZmH +Nmn - matom) x(931.49)
- peaks ingraph are due to closed shells
- nuclear force is a short-ranged force
- heavier nuclei can become more stable by breaking into smaller pieces
- lighter nuclei can become more stable by fusing together
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