# Oscillation of one molecule or atom

• mpocciot
In summary, atoms vibrate as a result of heat energy transfer, and this vibration can be observed using spectroscopy.

#### mpocciot

Hello all,

Many Physics texts simply say that atoms "vibrate" when heat energy is transfer to a metal bar when it is heated. Or that molecules vibrate as the result of heat transfer.
I'm trying to understand what makes an atom or molecule "move" or oscillate when energy is given to it.
If I have only one molecule in a region of space with no other molecules or atoms around it and a beam of light from the sun hits it, the molecule will oscillate up and down because of the electromagnetic fields? It is just a matter of electric charges in the molecule moving in a field?

I don't think the atoms would absorb energy and start to move by themselves as if something inside the particles were creating that motion like a mexican jumping bean. Either they move as a result of momentum being transferred or by the charges being submitted to an electromagnetic field (or even because of a gravitational field acting upon its mass)

In brownian motion we know that the molecules move as the result of numerous collisions they undertake one another. But what if I have only one molecule?

many thanks for any comments.

Cheers,

Marcio

Oscillations or vibrations occur under the control of a restoring force.
They cannot occur without this second agent.

Have you done simple harmonic motion?

In an aggregate of atoms the restoring force is provided by interatomic forces.

A single isolated atom cannot vibrate, mechanically.

It can, however be involved in collisions with other particles and suffer change of momentum.
Photons have momentum.
However they are so small they are will affect individual parts of the atom rather than the atom as a whole, particularly the outer electrons.

Atoms are electrically neutral so in general they can't interact with electromagnetic fields.
However they also have physical size and they are neutral because they contain an equal number of positive and negative charges.
These charges are not all in one place but are distributed within the atom.
This leads to the atom being able to act like a dipole or quadrupole and participate in vibrations in EM fields. This is how NMR works.

Does this help?

It will oscillate if it's charged. A neutral molecule may also rotate or vibrate internally if it has an electric dipole change associated with that movement.

Hi Studiot,

thanks, it helps.

MArcio

Atoms cannot vibrate alone. They also cannot rotate. In chemistry atoms are treated as point particles for purposes of rotational and vibrational spectroscopy.

However molecules can rotate and vibrate; when they vibrate at their normal modes, they can emit radiation (usually in the IR band) at the frequency of these normal modes.

chill_factor said:
Atoms cannot vibrate alone. They also cannot rotate. In chemistry atoms are treated as point particles for purposes of rotational and vibrational spectroscopy.

However molecules can rotate and vibrate; when they vibrate at their normal modes, they can emit radiation (usually in the IR band) at the frequency of these normal modes.

How can a single atom NOT rotate alone? that doesn't make much sense, ofcourse for mathematical purposes a rotating single atom may be the same as a still one(apart from... magnetism?) but if you shoot light at it from an angle, it should using common sense, be shocked away in a spinning momentum, assuming it reflects the light.

## 1. What is oscillation of one molecule or atom?

Oscillation of one molecule or atom refers to the periodic back-and-forth movement of a single molecule or atom around its equilibrium position. This movement is caused by a restoring force that pulls the molecule or atom back towards its starting point.

## 2. How does oscillation of one molecule or atom occur?

Oscillation of one molecule or atom occurs when the molecule or atom is subjected to a force that causes it to deviate from its equilibrium position. This deviation results in a restoring force that brings the molecule or atom back to its starting point, creating a repeating cycle of back-and-forth movement.

## 3. What factors affect the oscillation of one molecule or atom?

The oscillation of one molecule or atom can be affected by factors such as the strength of the restoring force, the mass of the molecule or atom, and the frequency of the oscillation. Additionally, external factors like temperature and pressure can also influence the oscillation of a molecule or atom.

## 4. What is the importance of studying the oscillation of one molecule or atom?

Studying the oscillation of one molecule or atom can provide insight into the behavior and properties of matter at the molecular and atomic level. It also has practical applications in fields such as chemistry, physics, and materials science, where understanding the movement of individual molecules and atoms is crucial.

## 5. How can we measure the oscillation of one molecule or atom?

The oscillation of one molecule or atom can be measured using techniques such as spectroscopy, which can detect the frequency and amplitude of the oscillation. Other methods include atomic force microscopy and laser interferometry, which can directly observe the movement of individual molecules and atoms.