Quantum Mechanics Flashcards

1
Q

Quantum chemistry and its application to spectroscopy

A

Classical experiments
Principle of quantum mechanics
Molecular orbital theory
Molecular spectroscopy

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2
Q

Black body radiation

A

Thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a blackbody

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3
Q

Radiant excitance

A

Glowing radiation caused by the heating up a a material i.e. Tungsten filament

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4
Q

Blackbody

A

A perfect absorber that is a substance that absorbs all frequencies of light and emits none; it would be black

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5
Q

Quanta

A

Discrete units of light energy; the energy of a quantum was directly proportional to a frequency of an oscillator; E = hv

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6
Q

Photoelectric effect

A

e- are mutter from a metal when the metal is irradiated with visible/ UV radiation

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7
Q

Photoelectric effect 1st observation

A

Below a given cutoff frequency of incident radiation, no e- were ejected from the metal surface, no matter how intense the radiation

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8
Q

Photoelectric effect 2nd observation

A

Above the cutoff frequency, the # of e- emitted was directly proportional to the intensity of the radiation

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9
Q

Photoelectric effect 3rd observation

A

As the frequency of the incident radiation increased, the maximum velocity of the ejected e- increased

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10
Q

Photons

A

Light particles

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11
Q

Einsteins Equation for photoelectric effect

A
ha = 1/2•mv^2 + w,
w = working energy,
1/2•mv^2 = kinetic energy of emitted electron
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12
Q

Dual nature of radiation

A

Light can be both a particle and a wave; wavelength = h/p = h/mv,
p = momentum, h = Planck’s constant

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13
Q

Planck’s constant

A

6.626x10^-34 J/s

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14
Q

Heisenberg uncertainty principle

A

It is impossible to simultaneously measure the momentum and position of a particle such as an e-, because performing one measurement would disturb the particle and prevent the accurate measurement of the 2nd quantity

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15
Q

Heisenberg uncertainty principle expression

A

dq•dp > h/4pi; the product of the uncertainty of the position (dq) and the uncertainty of the momentum (dp) is greater than h/4pi

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16
Q

Principles of quantum mechanics

A

Has 5 postulates

17
Q

1st postulate of quantum mechanics

A

The physical state of a particle can be fully described by a wave function of type x,y,z,t

18
Q

2nd postulate of quantum mechanics

A

The x,y,z,t wave functions are obtained by solving the appropriate schrodinger equation.

19
Q

Shrodinger equation: for time-independent systems

A
h^2/8pim• 💎^2¥ + [E-V(r)]¥ =0,
💎= laplacian operator in units m^-2
V = potential energy
¥ = position-space wave function m^-3/2
E = energy in J
h = Planck's constant
M = mass in kg
20
Q

3rd postulate of quantum mechanics

A

Every dynamic variable that correlates with a physically observable property is expressed as a linear operator

21
Q

4th postulate of quantum mechanics

A

Operators that represent physical properties are derived from the classical expressions for these properties

22
Q

5th postulate of quantum mechanics

A

The eigenvalues obtained by solving the appropriate schrodinger equation represent all possible values of an individual measurement of the quantity in question

23
Q

Operators

A

Represented with a circumflex accent over the symbol that represents the variable in interest

24
Q

Shrodinger equation

A

A complex wave function used to describe the quantum mechanical state of a particle

25
Probability density (w)
The probability of finding a particle at time t at a give position r = x,y,z in a volume dV; w = |¥|^2dV
26
Time-dependent wave function
Used to describe the harmonic wave motion of a free particle
27
Time dependent wave function
``` ¥(r,t) = (a)e^i[wt-(k•r)]; a = amplitude in units of m^-3/2 i = imaginary unit =(sqrt(-1)) w = frequency k= wave number vector r = radius vector describing the position of the particle in space ```
28
Eigenfunctions
Solutions to the schrodinger equation, and they exists only for specific eigenvalues of energy
29
Eigenvalues
The totality of them for E yields the tire energy spectrum of the particle
30
Harmonic oscillator
A particle that has mass m which, under the influence of a linearly applied force, will move in one or several directions with a frequency of w0
31
Schrodinger equation for one-dimensional harmonic oscillator
d^2¥/dx^2 + 8pim/h^2•[E-(mw0^2/2)x^2]¥ = 0
32
Zero point energy
The lowest energy possible for the harmonic oscillator
33
Harmonic oscillator is used to model:
The vibrations of atoms and molecules | The lattice vibrations of crystalline materials