Ground state and stationary states

In summary, the ground state is the lowest energy state of an atom or molecule, while stationary states refer to any energy state that is not changing over time. Electrons can transition between these states by absorbing or emitting energy in the form of photons. It is possible for a system to be in multiple stationary states at once, known as superposition. The concepts of ground state and stationary states are crucial in understanding an atom's spectral lines, which can be used to identify elements in a substance. While these states cannot be observed directly, their effects can be observed through experiments and measurements.
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Einstein Jr.
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Can you please explain the difference between ground state and stationary state? In the stationary state, are the electrons at rest inside the atom?
 
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A stationary state is, by definition, a state, where nothing changes in time. In atomic physics it's the eigenstate of the Hamiltonian of the atom (usually sufficiently described as a "point like" positively charged nucleus and electrons, leading to an overall electrically neutral bound system), neglecting the coupling of the charges to the fluctuating electromagnetic field.

The ground state is the state of lowest energy, and thus it is stable also when taking the coupling to the fluctuating radiation field into account. All the other stationary states, the excited states, are in fact instable when you take the coupling to the fluctuating radiation field into account and thus emit after some time (which cannot be predicted, because this is a random process according to quantum theory) a photon leaving the atom in a lower stationary state.
 
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Einstein Jr. said:
Can you please explain the difference between ground state and stationary state?
The ground state is a stationary state: the one with lowest energy. Stationary states with higher energy are excited states.
Einstein Jr. said:
In the stationary state, are the electrons at rest inside the atom?
In a stationary state, the position probability distribution of an electron does not change with time. Nor does the momentum probability distribution. QM does not address the question of what an electron is "really doing", "inside" the probability distribution, before something happens that "measures" the position or momentum.
 

FAQ: Ground state and stationary states

1. What is the difference between ground state and stationary states?

The ground state is the lowest energy state that an atom or molecule can occupy, while stationary states refer to any energy state that is not changing over time. In other words, the ground state is a specific stationary state, but not all stationary states are ground states.

2. How do electrons transition between ground state and stationary states?

Electrons can transition between ground state and stationary states by either absorbing or emitting energy in the form of photons. When an electron absorbs energy, it moves to a higher stationary state, and when it emits energy, it moves to a lower stationary state.

3. Can a system be in multiple stationary states at once?

Yes, a system can be in multiple stationary states at once. This is known as superposition and is a fundamental principle in quantum mechanics. In fact, it is the basis for the famous Schrödinger's cat thought experiment.

4. How do ground state and stationary states relate to an atom's spectral lines?

Ground state and stationary states play a crucial role in an atom's spectral lines. When an electron transitions between these states, it emits or absorbs photons of specific energies, which correspond to specific spectral lines. This allows scientists to identify the elements present in a substance by analyzing its spectral lines.

5. Can ground state and stationary states be observed directly?

No, ground state and stationary states cannot be observed directly because they are quantum states, and the act of observation would collapse the system into a single state. However, their effects can be observed through experiments and measurements, such as in spectroscopy and quantum computing.

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