Timeline for Calculating total fluorescence based on thin slices in a slab
Current License: CC BY-SA 4.0
13 events
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| Jan 7, 2023 at 17:47 | comment | added | rdemyan | But I find that if I multiply all of the simulated fluorescence values (values at each time step) by a single constant value, then the profiles will match reasonably well. So a single correction factor applied to the entire simulation fluorescence curve will result in it matching the experimental curve. I have been puzzled by why this is the case. Perhaps it is due to the cautions that you outline in your post. Unfortunately, I don't feel that I have a full understanding of the issues that you bring up. | |
| Jan 7, 2023 at 17:44 | comment | added | rdemyan | @Curt F. The procedure I outlined above is for a specific time. My simulation actually runs for about a thousand iterations or so, so from time, t = 0 to t = tfinal. My simulated total fluorescence as a function of time profile is then compared to the experimental one. I guess values of the slab thickness until the profiles match. For about 25% of my data, no correction value is needed in order to get the profiles to match (at a specific value of L). However, for the other 75%, the simulation seems to understimate the fluorescence when compared to the experimental fluorescence. | |
| Jan 7, 2023 at 17:32 | comment | added | Curt F. | Your method seems fine, as long as your excitation light source is strong enough in intensity. You don't want the light absorption by any of your slices to significantly affect the excitation intensity in the layer below. Also, you might want to make sure that the absorbance of your "slices" for the emitted light is negligible too. If both of these assumptions are met, then each slice really is independent of the adjacent ones, and you can probably add up all the fluorescence to get the total | |
| Jan 7, 2023 at 17:19 | comment | added | rdemyan | Finally, all of the slice fluorescences are summed to get the total fluorescence for the two half slabs, which is a thickness of 2L (see my previous comment on half slab thickness). Please let me know if this is not what you mean. | |
| Jan 7, 2023 at 17:19 | comment | added | rdemyan | The pH for a slice is calculated from Fick's diffusion model (attached diagram shows the concentration profiles (or alternatively, pH profiles) at a specific time, t). Then the equation is used to get the fluorescence at that pH. The equation, however, provides a fluorescence value for a known thickness, sm. So to get the fluorescence for the slice, multiply the calculated fluorescence by the slice thickness, dx, divided by the thickness, sm. The foregoing is accomplished for all slices in both half slabs. Comment continues below..... | |
| Jan 7, 2023 at 17:18 | comment | added | rdemyan | @porphyrin: Let me make sure I understand what you are saying. You are saying that I just add the calculated fluorescence value for the base slab to the calculated fluorescence value for the acid slab. If so, that is what I have been doing. However, in each slab the pH is not constant; hence the slices for each slab. The pH/fluorescence equation that I have is based on a thickness, sm. I am calculating the pH and then fluorescence for each slice where it is assumed that these values are constant within the thin slice. Comment continues.......... | |
| Jan 7, 2023 at 17:15 | answer | added | ACR | timeline score: 2 | |
| Jan 7, 2023 at 16:58 | comment | added | rdemyan | The figure is just meant to provide an idea of the concentration profiles at a specific time. Where the curves go to zero is the reaction plan of acid and base. The mathematical model assumes that acid and base cannot coexist and sets this value as zero. However, as mentioned above, the value is actually 10-7, which for all practical purposes is zero and does not affect any model calculation determining the pH of the curves. The curves are theoretical. On the x axis the values can be listed as -L on the left side and +L on the right side. L is the half slab thickness. | |
| Jan 7, 2023 at 16:56 | comment | added | porphyrin | You say you have fluorescence yield vs pH, (f(pH) )so the total will be weighted according to this, so you have f(pH)Conc(acid)+f(pH)Conc(base) = total fluorescence so you seem not to have enough information, one measurement but two values you need. But I'm not clear about what you are actually doing | |
| Jan 7, 2023 at 10:21 | comment | added | Maurice | What is the meaning of the two curves c(x,t) going to zero in the middle of the diagram ? Are the curves theoretical or experimental ? Why are there no numerical values on the Ox axis ? Why is the time not mentioned ? | |
| Jan 6, 2023 at 22:58 | comment | added | rdemyan | Yes, I am using umbelliferone in both the acid and base and the concentrations are the same, so there is no diffusion gradient for the umbelliferone. I did not mean to mislead regarding the pH7. A pH of 7 is definitely fluorescent. I was just showing the concentration gradients and that bit of information is more important for the analytical model than for my question. Sorry to confuse and thanks for bringing up the point about possible diffusion of the umbelliferone. Any thoughts on my question regarding adding up the slice fluorescences to get the total for both half slabs? | |
| Jan 6, 2023 at 20:04 | comment | added | Maurice | Is the fluorescent emitter the same in both acidic and basic solutions ? Why do you think the neutral mixture is not fluorescent ? | |
| Jan 6, 2023 at 19:30 | history | asked | rdemyan | CC BY-SA 4.0 |