/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 26 The oscillation of the atoms aro... [FREE SOLUTION] | 91Ó°ÊÓ

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The oscillation of the atoms around their equilibrium positions in the molecule HI can be modelled as a harmonic oscillator of mass \(m \approx m_{\mathrm{H}}\) (the iodine atom is almost stationary \()\) and force constant \(k_{\mathrm{f}}=313.8 \mathrm{N} \mathrm{m}^{-1} .\) Evaluate the separation of the energy levels and predict the wavelength of the light needed to induce a transition between neighbouring levels.

Short Answer

Expert verified
The separation of energy levels is calculated to be \(2.43 x 10^{-20}\) Joules, and the corresponding wavelength of light required to induce a transition between neighbouring levels is calculated to be \(8.14 x 10^{-6}\) meters or \(8140\) nanometers.

Step by step solution

01

Calculation of Energy level separation

The formula for energy levels in a quantum harmonic oscillator is given by: \(E_n = \left(n + \frac{1}{2}\right)hv\) with \(v\) the frequency of oscillation, \(h\) is Planck's constant and \(n\) being an integer as the quantum number (number of levels). But, \(v\) can be calculated from the force constant and mass using the formula: \(v = \frac{1}{2\pi}\sqrt{\frac{k_{f}}{m}}\). Substitute this expression of \(v\) into the energy level formula to get: \(E_n = \left(n + \frac{1}{2}\right)h\frac{1}{2\pi}\sqrt{\frac{k_{f}}{m}}\). The difference between two successive levels (i.e. separation) is: \( \Delta E = E_{n+1} - E_n = h\frac{1}{2\pi}\sqrt{\frac{k_{f}}{m}}\). Substitute the known values into this equation to find the separation.
02

Calculation of Wavelength

Now we'll use the Planck-Einstein relation to calculate the wavelength: \(E_{\text{photon}} = hf = \frac{hc}{\lambda}\). The energy of the photon is equal to the separation of the energy levels we just calculated: \(\frac{hc}{\lambda} = \Delta E\). Rearrange this equation for \(\lambda\): \(\lambda = \frac{hc}{\Delta E}\). Substitute the values into this equation to get the wavelength.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Energy Level Separation
Energy level separation in a quantum harmonic oscillator refers to the difference in energy between two consecutive quantum states. Each energy level in the system is quantized, meaning only specific amounts of energy are allowed. This separation can be found using the formula:\[ \Delta E = E_{n+1} - E_n = h\frac{1}{2\pi}\sqrt{\frac{k_{f}}{m}} \]Here, \(h\) is Planck's constant, \(k_f\) is the force constant, and \(m\) is the mass of the oscillating particle. This formula shows that the separation depends directly on the frequency, which is derived from the force constant and mass.Understanding these separations is key to grasping how quantum systems like molecules absorb and emit energy. For the HI molecule, the higher the force constant, the larger the energy separation, affecting how it interacts with electromagnetic radiation.
Planck's Constant
Planck's constant \(h\) is one of the most critical constants in quantum mechanics, linking the energy of a photon to its frequency via the equation:\[ E = hf \]This constant is crucial in calculations of energy differences in quantum systems like the harmonic oscillator. With a value of approximately \(6.626 \times 10^{-34} \text{Js}\), it reveals the discrete nature of energy in quantum mechanics. In contexts such as the HI molecule, it helps calculate the precise energy levels and their separations.Understanding Planck's constant is essential for exploring the quantum world, where energies are not continuous but come in quantized steps. It also underpins technologies like lasers and quantum computing by allowing for precise energy control.
Frequency of Oscillation
The frequency of oscillation \(v\) in a quantum harmonic oscillator characterizes how rapidly the particle vibrates around its equilibrium position. It is derived from the formula:\[ v = \frac{1}{2\pi}\sqrt{\frac{k_{f}}{m}} \]- \(k_f\) represents the force constant of the oscillator.- \(m\) is the mass of the oscillating atom or particle.The frequency is central to determining the energy levels. In the case of a molecule such as HI, the iodine is considered stationary, making the hydrogen atom the primary oscillating mass. A higher frequency indicates more energy in the vibrations, leading to greater energy level separations. This frequency impacts the type of electromagnetic radiation the molecule can absorb or emit, making it pivotal in spectroscopy.
Wavelength Calculation
Once the energy level separation is known, the wavelength of light necessary for a transition between these levels can be calculated using the Planck-Einstein relation:\[ E_{\text{photon}} = \frac{hc}{\lambda} \]Rearranging gives us:\[ \lambda = \frac{hc}{\Delta E} \]- \(c\) is the speed of light, approximately \(3 \times 10^8 \text{ms}^{-1}\).- \(\Delta E\) is the energy level separation, which you previously calculated.This formula shows how the energy difference affects the light wavelength required for transitions. In the HI molecule, knowing \(\Delta E\) allows the prediction of the specific wavelength needed to induce transitions, enabling precise experimental measurements and spectral analysis. By manipulating these ideas, scientists can ascertain physical properties of molecules and their interactions with light. Understanding this relationship is vital for interpreting spectroscopic data and various applications in quantum chemistry and physics. It connects energy changes directly to observable light properties.

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Most popular questions from this chapter

A very simple model of a polyene is the free electron molecular orbital (FEMO) model. Regard a chain of \(N\) conjugated carbon atoms, bond length \(R_{\mathrm{CC}},\) as forming a box of length \(L=(N-1) R_{\mathrm{CC}} .\) Find an expression for the allowed energies. Suppose that the electrons enter the states in pairs so that the lowest \(\frac{1}{2} N\) states are occupied. Estimate the wavelength of the lowest energy transition, taking \(R_{\mathrm{CC}}=140 \mathrm{pm}\) and \(N=22 .\) Repeat the calculation of the wavelength if the length of the chain is taken to be \((N+1) R_{\mathrm{CC}}(\) an assumption that allows for electrons to spill over the ends slightly.

Calculate the energies and wavefunctions for a particle in a one-dimensional square well in which the potential energy rises to a finite value \(V\) at each end, and is zero inside the well; that is \\[ \begin{array}{ll} V(x)=V & x \leq 0 \text { and } x \geq L \\ V(x)=0 & 0

Energy is required to compress the box when a particle is inside: this suggests that the particle exerts a force on the walls. (a) On the basis that when the length of the box changes by dL the energy changes by \(\mathrm{d} E=-F \mathrm{d} L,\) find an expression for the force. (b) At what length does \(F=1 \mathrm{N}\) when an electron is in the state \(n=1 ?\)

Locate the nodes of the harmonic oscillator wavefunction for the state with \(v=6 .\) Hint. Use mathematical software.

Determine the probability of finding the ground-state harmonic oscillator stretched to a displacement beyond the classical turning point. Hint. Relate the expression for the probability to the error function, erf \(z,\) defined as \\[ \operatorname{erf} z=1-\frac{2}{\pi^{1 / 2}} \int_{z}^{\infty} \mathrm{e}^{-y^{2}} \mathrm{d} y \\] and evaluate it using erf \(1=0.8427 .\) The error function is incorporated into most mathematical software packages.

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