I'm still looking for an article/graph I saw where it measured photosynthesis 24hrs light and dark by the hour. I believe it showed that photosynthesis rose in the morning, like the sun, using the most CO2 later in the day and evening, even after the light went down for a while. Morning less use, midday starting to climb, afternoon and evening a couple of hours into night the highest CO2 use, then it dropped drastically at midnight or so......the best of my recollection. I remember because it was interesting to know that you could do without CO2 until later in the day, and keep it on until midnight. Problem is, I can't find the article. Most graphs show photosynthesis in general from sun up to sundown. Not specifically CO2 usage, like this article did.
If anyone finds this, be sure to post it! I could be totally wrong about this. Memory can be tricky.