I would scrump millions of photons together, and this would cause radiation to spread. This would wipe out the aliens
I'd produce the same effect the astronauts have in the moon, to the aliens. This way, their vision (if any) would be negatively affected, basically blinding them. These light flashes probably impair hearing and the other senses as well, so If their bodies are less developed, they would probably become senseless. Then, I would shoot and shoot and shoot and shoot till' dey' b' DED'