Full Excitation of Molecular Vibration Modes

In summary, the conversation discusses the relationship between Cp/R and temperature, and how it can be used to approximate the number of fully excited vibration modes for a given molecule. The speaker mentions that this is a relatively obscure problem and asks for a sample molecule to attempt it on. The conversation then delves into specific examples, such as monatomic gases, linear rotors, and different molecules, to explore the variations in Cp/R values. The speaker also asks about the difference in Cp/R values for flexible and rigid molecules and how it relates to the concept of "fully excited" vibration modes.
  • #1
VincentLaw
1
0

Homework Statement


Given the relationship Cp/R as a function of Temperature, approximate the number of fully excited vibration modes at a given temperature for a given molecule.

2. The attempt at a solution
I have looked through several textbooks and many web sites, but I can't find this type of problem discussed anywhere. vaguely similar problems I have found only assume given excitation states. It seems like a relatively obscure problem, but I assume there is a generic solution process.
 
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  • #2
I assume you are talking about degree of freedom, the total ways in which the molecule can exhibit motion, seeing you mentioned Cp/R.

Anyway, can you give a sample molecule on which you would like to attempt this question on?
 
  • #3
Let's think specifically about Cp/R

What is the value of Cp/R for a monatomic gas? is it the same for all monatomic gases?

Now what is it for a linear rotor? Is it the same for N2, O2, CO2?

What about I2 -- that value is a little bit different -- why?

What is the value of Cp/R for water? Methane? Could you tell whether SO2 was linear or bent by looking at Cp/R?

How and why does Cp/R differ for a really floppy molecule like 1-propanol and a really rigid molecule like benzene?

And if you can work your way through all of that you should have a really good idea about the relationship between Cp/R and "fully excited" vibrational modes.
 

1. What is full excitation of molecular vibration modes?

Full excitation of molecular vibration modes refers to the state in which all of the molecular vibration modes are simultaneously excited. This means that all of the atoms in the molecule are vibrating with maximum amplitude, resulting in a higher energy state.

2. How does full excitation of molecular vibration modes occur?

Full excitation of molecular vibration modes can occur through various methods, such as heating, exposure to electromagnetic radiation, or collisions with other molecules. These processes provide energy to the molecules, causing them to vibrate at higher frequencies and amplitudes.

3. What are the effects of full excitation of molecular vibration modes?

The effects of full excitation of molecular vibration modes depend on the specific molecule and its surrounding environment. In some cases, it can lead to changes in the molecule's shape and properties, such as increased reactivity or altered bonding. It can also result in the emission of light or heat, which can be used for various applications.

4. How is full excitation of molecular vibration modes studied?

Scientists study full excitation of molecular vibration modes through techniques such as infrared spectroscopy, Raman spectroscopy, and neutron scattering. These methods allow for the detection and analysis of the vibrations and their frequencies, providing valuable information about the molecule's structure and behavior.

5. What are some real-world applications of full excitation of molecular vibration modes?

Full excitation of molecular vibration modes has various practical applications, including in the fields of materials science, pharmaceuticals, and environmental monitoring. It can also be used in technologies such as lasers, sensors, and chemical analysis methods. Understanding and controlling molecular vibrations can lead to the development of new materials and improved processes in many industries.

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