First of all. We should mention that we use the intensity of absorption of the certain range of the spectrum to estimate the concentration of Sm2+. There exist two ways to change the value of reflectance to absorption, one is K-M equation, and the other one is based on the equation that A(absorption)+R(reflectance)+ T(transmittance)=1. Since the transmittance is definitely negligible for our sample, then the equation can be written as A+R=1, that is A=1-R, which is the equation we used here. Previously, I prepared a batch of sample of CaF2 with Eu and Sm co-doping. The concentration of Eu2+ is fixed as 1%, while for Sm3+, different values(0.5%, 1%, 2%, 4%) were chosen. From the final results, we found that the saturated absorption for Sm(1%, 2%, 4%) is almost the same, which is obviously higher than that of the sample with 0.5%Sm. Because the ability of absorption depends on the concentration of Sm2+.
Therefore, if the original concentration of Sm3+ is low, then the final number of the absorption centers Sm2+ would not be high as well even though we increase the irradiation time further. In other words, the designed concentration of Sm for the samples determine the ability of Sm2+ absorption. Why the absorption of the other three samples keeps almost the same? It can be interpreted that the conversion of Sm3+ to Sm2+ occur along with Eu2+ to Eu3+, and the designed concentration of Eu can limit the absorption of Sm2+. Since the fixed concentration of Eu2+ is just as much as 1%, then the concentration of Sm2+ can not exceed 1% theoretically no matter how long it has been irradiation by X-ray. To make the explanation more convincing, we prepared additional sample with the concentration of Eu and Sm of 1% and 0.01%, respectively, and the corresponding result conform to the explanation as well. A series of sample with the fixed concentration of Sm (1%) and variable concentration of Eu ()
- The range of 200-450 nm contain both the photoluminescence and reflectance, it is difficult to distinguish them, so the data is not reliable.
- To do the alignment, we choose a specific range not from 800nm, because it seems that something wrong when use those data 800-794 nm. We use the starting 5 to 15 points to make an alignment.
- When processing the data from csv file. The 2rd column and 4th colum means the baseline of the BaSO4 reference and non-reference. The other data are the results processed from the two baselines?
- When measuring two samples in the folder of Eu variation, two(?) samples shows a reflectance of ZERO at around 800 nm, then jump up to the normal values. So when make an alignment, we avoid the area.
我先前制备了一组Eu-Sm组分的CaF2样品，其中Eu的浓度固定为1%，变化Sm的浓度（0.5%，1%，2%，4%）,
Is it possible to directly choose absorption when we measure the samples?