# Relation between enthelpy of sublimation and rate of sublimation?

• DenisH
This conversation discusses the challenges of determining the sublimation rate of a material under high-temperature, high-vacuum conditions. The speaker mentions using the material's saturated vapor pressure to calculate the sublimation rate, but notes that this information is not available for the specific material they are working on. They also mention the enthalpy of sublimation, but have not found a direct relationship between it and the sublimation rate. Their question is whether such a relationship exists.

#### DenisH

TL;DR Summary
Is there a way to get the rate of sublimation of a material in vacuum for a given temperature from its enthalpy of sublimation?
Hello,
I am running experiments where materials are heated at high temperatures during tens of hours under high-vacuum conditions. Since what I am investigating lies in the first hundreds of nanometers of the materials, I must take into account (and anticipate) surface sublimation.
Therefore I am trying to determine at which rate a sample surface is sublimating. I found that this can be calculated from saturated vapor pressure, giving results in consistent with my experimental observations. Unfortunately for the material I am working on (UO2+x), no such saturated vapor pressure has ever been published... but enthalpy of sublimation had been.
At this stage I did not found a relation between enthalpy of sublimation and sublimation rate (or saturated vapor pressure)... my question thus is: is there one?
Thank you

DenisH said:
Summary:: Is there a way to get the rate of sublimation of a material in vacuum for a given temperature from its enthalpy of sublimation?

my question thus is: is there one?
No.

DenisH

## 1. What is the definition of enthalpy of sublimation?

The enthalpy of sublimation is the amount of energy required to change a substance from a solid to a gas without going through the liquid phase.

## 2. How does the enthalpy of sublimation affect the rate of sublimation?

The higher the enthalpy of sublimation, the slower the rate of sublimation. This is because more energy is needed to break the bonds between solid particles and turn them into gas particles.

## 3. What factors can influence the enthalpy of sublimation?

The enthalpy of sublimation can be influenced by the strength of intermolecular forces, the size and structure of the molecules, and the temperature and pressure of the environment.

## 4. How does temperature affect the rate of sublimation?

Generally, an increase in temperature leads to a higher rate of sublimation. This is because higher temperatures provide more energy for the particles to overcome the intermolecular forces and transition from solid to gas.

## 5. Can the rate of sublimation be manipulated by changing the pressure?

Yes, the rate of sublimation can be manipulated by changing the pressure. Higher pressures can decrease the rate of sublimation, while lower pressures can increase it. This is because pressure affects the energy required for the particles to overcome intermolecular forces and transition from solid to gas.