# Calculating the threshold ionization intensity for hydrogen gas.

• Cypher49
In summary, for the given problem of calculating the threshold ionization intensity for hydrogen gas, the attempt at a solution involved using the field intensity of air, which breaks down at 3x10^6V/m. However, it was pointed out that gases have a threshold ionization energy, not intensity. The ionization potential of hydrogen was stated to be 13.598ev, while the oxygen and nitrogen values were deemed irrelevant. The discussion then shifted to the possibility of the question being about dielectric strength, but the calculation of this value was not known. It was suggested to assume room temperature and 1 atmosphere pressure, but the person posing the question was unsure if this was correct. The purpose of solving this problem was said to
Cypher49
Homework Statement
Calculate the threshold ionization intensity for hydrogen gas.

The attempt at a solution

The way I tried to work it out was to use the field intensity of air which breaks down at, 3x10^6V/m. The ionization potential of oxygen is 13.618ev, 14.534ev for nitrogen and 13.598ev for hydrogen. So I was thinking that the ionization potential of air would be around the same for hydrogen.

Am I on the right track with this?

Anyone?

Cypher49 said:
Homework Statement
Calculate the threshold ionization intensity for hydrogen gas.

The attempt at a solution

The way I tried to work it out was to use the field intensity of air which breaks down at, 3x10^6V/m. The ionization potential of oxygen is 13.618ev, 14.534ev for nitrogen and 13.598ev for hydrogen. So I was thinking that the ionization potential of air would be around the same for hydrogen.

Am I on the right track with this?
The problem is worded strangely. Gases have a threshold ionization energy (not intensity). In which case the threshold for hydrogen is the energy value you said for hydrogen -- the oxygen and nitrogen values are irrelevant.

Did you type the problem statement exactly, word-for-word? And included all the given information?

I wrote exactly what was in the question, and it's not possible to go check this as the academic year is over and school is closed.

So the threshold ionization energy of hydrogen is 13.598ev right?

One thing that I didn't write was that the answer should be in V/m.
So I think that the answer for the question is just the dielectric strength of hydrogen which is 1.75x10^6 isn't it?

The person who wrote the question probably messed up.

Okay, if they were really talking about dielectric strength ... I don't know how to calculate that, but it does depend on the gas density (or equivalently, pressure/temperature). Usually room temperature is assumed unless they say otherwise. But the pressure is unspecified, perhaps you are to assume 1 atmosphere? What class was this for?

Presumably you were shown some way to calculate this at some point during your school term? And when they say to calculate it, I would expect that looking up (or knowing, from having memorized it) the value would not earn much credit for solving the problem.

(Or, as you said, the person who wrote the question could have messed up.)

You don't need to show the working out, our teacher likes to give his students a problem to solve where the answer isn't so obvious from a google search.

For getting the right answer you get first pick of seats for the new year and our names get put into a raffle to win one of those space pens (however some of us think he's just going to give us a pencil).

Is the 1.75x10^6V/m figure correct for hydrogen at room temperature and 1 atmosphere?

## 1. What is the threshold ionization intensity for hydrogen gas?

The threshold ionization intensity for hydrogen gas is the minimum amount of energy required to remove an electron from a hydrogen atom, resulting in the formation of a positively charged ion. This energy is typically measured in units of energy per unit area, such as watts per square centimeter (W/cm2).

## 2. How is the threshold ionization intensity for hydrogen gas calculated?

The threshold ionization intensity for hydrogen gas can be calculated using the formula Ith = 13.6 eV / (4πr02), where Ith is the threshold ionization intensity, r0 is the Bohr radius (0.529 Å), and eV is the unit for energy. This formula takes into account the energy required to overcome the binding energy of the electron in the hydrogen atom.

## 3. What factors can affect the threshold ionization intensity for hydrogen gas?

The threshold ionization intensity for hydrogen gas can be affected by factors such as the wavelength of the incident light, the gas pressure, the temperature, and the presence of other atoms or molecules in the gas. These factors can alter the energy levels of the electrons in the hydrogen atoms, thus changing the amount of energy needed for ionization.

## 4. Can the threshold ionization intensity for hydrogen gas be experimentally measured?

Yes, the threshold ionization intensity for hydrogen gas can be experimentally measured using various techniques such as photoelectron spectroscopy or optical spectroscopy. These methods involve shining a laser or other light source onto the gas and measuring the energy of the emitted electrons to determine the threshold ionization intensity.

## 5. Why is the threshold ionization intensity for hydrogen gas important?

The threshold ionization intensity for hydrogen gas is important because it provides valuable information about the energy levels and structure of the hydrogen atom. It is also a key parameter in many industrial and scientific applications, such as laser ablation, plasma generation, and chemical analysis using mass spectrometry.

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