What speed must the electrons reach by the moment of collisions with the molecules in order

| March 15, 2021 | education

What speed must the electrons reach by the moment of collisions with the molecules in order for the impact ionization to begin in nitrogen? The ionization energy of nitrogen molecules is 14.5 eV. How to find m?

W = 14.5 eV = 23.2 * 10 ^ -19 J.

m = 9.1 * 10 ^ -31 kg.

V -?

According to the law of conservation of energy, the kinetic energy of a moving electron Ek should be sufficient to break the binding energy in the molecule W: Ek = W.

We express the kinetic energy of the electron Ek by the formula: Ek = m * V2 / 2, where m is the mass of the electron, V is the speed of motion of the electron.

The electron mass m is a tabular value, which is m = 9.1 * 10 ^ -31 kg.

V = √ (2 * W / m).

The ionization energy of the W molecule is converted into SI units. Energy 1 eV = 1.6 * 10 ^ -19 J, therefore W = 14.5 eV = 14.5 * 1.6 * 10 ^ -19 J = 23.2 * 10 ^ -19 J.

V = √ (2 * 23.2 * 10 ^ -19 J / 9.1 * 10 ^ -31 kg = 2.24 * 10 ^ 6 m / s.

Answer: before hitting the molecule, the electron had a speed of V = 2.24 * 10 ^ 6 m / s.



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