Now I'm describing something, the character of an electron is fishy to me because
1) The structure of electron is unknown
2) And why an electron is excited(after absorbed photon) to a higher energy level when the rest MASS OF PHOTON is 0 !
When an electron is excited from a lower to a higher energy level, it will not stay that way forever. An electron in an excited state may decay to a lower energy state which is not occupied, according to a particular time constant characterizing that transition. When such an electron decays without external influence, emitting a photon, that is called "spontaneous emission". The phase associated with the photon that is emitted is random.
I thought something about bound electrons to change their orbits after absorbed photons. Simply I guessed that moon can change its orbit if we reduce/increase its enough mass by spacecrafts suddenly.
So what is happening, when a photon stricks a bound electron ! Is the energy of photon transformed into mass that increased the mass of electron after absorbed it (photon) !!
Or some times,(when an electron absorbed another photon from exited state to go lower state) is it happening like reduce its(electron) little bit of mass but transforms(reduced mass) into energy and carry the energy to re_emit !
And only a question that "Can cathode ray absorb photon(from laser or other source) before reached anode ?
Phew, quite a few things here but I'll have a go. Maybe a real physicist can add to or correct what I say in response.
To start with, I think you are somewhat "begging the question" with your first statement. According to my understanding of our current model, the electron has
no structure. There is no evidence for any structure and thus no need to hypothesise about it having any.
Secondly, on your point about photons, rest mass and energy, photons carry energy (E=hν), but this energy is due to them being disturbances in the electromagnetic field, rather than being due to the kinetic energy of a particle with rest mass. (Electric and magnetic fields contain stored energy, as you may know from the "pop" you sometimes hear when an accelerating electric train suddenly cuts off the power - that pop is the stored energy in the magnetic fields of the motors discharging, in the form of an electric arc).
As for what happens when a bound electron absorbs a photon, its potential and kinetic energy are increased. To use your space analogy, it is like an orbiting satellite being boosted into a higher orbit by a rocket motor giving it more speed. The satellite's rest mass is not increased by this, but it gains kinetic and gravitational potential energy. The only thing you have to bear in mind with electrons is that, being quantum-scale objects, they do not behave exactly like an orbiting satellite, because of their wavelike nature.
The means by which an electron emits or absorbs a photon can again be thought of in terms of the photon being a linked pair of oscillating electric and magnetic fields, whereas an electron is a charged particle in motion. Thinking of it in classical terms for a moment, an oscillating electric field of the right frequency can match the motion of the electron and thus amplify its motion (being charged, the electron will tend to move towards the +ve side of the field, so with an oscillating field the electron will tend to oscillate in sympathy). This transfers energy to the electron. In QM terms it is not quite like that, but it is sort of analogous. Emission is the reverse: classically, the oscillation of the electron would be expected to create an oscillating electric field, which radiates energy, thus reducing the kinetic and potential energy of the electron. (In fact, historically, this led to one of the objections to the classical Bohr model of the atom, with particle-like electrons orbiting the nucleus. They ought, by classical theory, to radiate away energy and spiral into the nucleus! The fact that they don't was one piece of evidence for quantisation. In QM they can radiate, but only in quantised jumps - and thus only at certain set frequencies - because a bound electron can only exist in a limited number of "standing wave" states.)
As to your last question about cathode rays absorbing photons from a laser, I would think the answer must be no, since a free electron is - according to my understanding - forbidden from absorbing. (If an electron is in a container such as a cathode ray tube, then you might think that, strictly speaking, it would behave like the well-known "particle in a box" scenario, in which case its translational energy would be quantised into a series of extremely closely spaced energy levels. However, since the anode attracts the electrons, one end of the "box" is effectively "open" in this case, so it seems to me there is no confinement of the electrons and no quantisation would be expected.)
If rpenner were answering this you would get a more correct answer, at the expense of needing a lot more QM terminology. I am trying to keep it pictorial so I am using a semi-classical approach.
(shakes head)--carry on.
