. Carnegie Institution of Washington publication. 66 STUDIES IN LUMINESCENCE. / and I~- is linear for small values of /. Since the early portion of each decay curve is chiefly determined by the first two or three points, which are the most difficult to observe, the values plotted for I0 are subject to considerable error. Curve A is nevertheless reasonably smooth and indicates nearly exact proportionality between intensity of excitation and. 20 4-0 60 80 100 Seconds Fig. 57- Effect of varying the intensity of the exciting light (as indicated on each curve). Exposure 2 minutes in each case. init
. Carnegie Institution of Washington publication. 66 STUDIES IN LUMINESCENCE. / and I~- is linear for small values of /. Since the early portion of each decay curve is chiefly determined by the first two or three points, which are the most difficult to observe, the values plotted for I0 are subject to considerable error. Curve A is nevertheless reasonably smooth and indicates nearly exact proportionality between intensity of excitation and. 20 4-0 60 80 100 Seconds Fig. 57- Effect of varying the intensity of the exciting light (as indicated on each curve). Exposure 2 minutes in each case. initial phosphorescence. It is only with the most intense excitation used that saturation begins. It is to be observed that in most cases the values of I0 that are computed from the data of Fig. 55 lie on the same curve as those obtained from the data of Fig. 57. A well-marked difference is noticeable only in 300 200 100 ^^ X J3--""" / M X'~'' X Fig: 58. Effect of the intensity of the excitation upon the initial intensity of phosphorescence. The points marked by dots are for an exposure of 2 minutes; those indicated by crosses are for an exposure of 20 seconds. In curves B and C the ordinates show the intensity of phos- phorescence 1 minute after excitation hail ceased. 10 20 30 Intensity of excitation 40 the case of the points corresponding to intense excitation. In other words, for weak excitations the intensity of the initial phosphorescence is the same after an exposure of 20 seconds as for 1 or 2 minutes. There at first appears to be a contradiction here to the results shown in Figs. 53 and 54. But while this may be due to the uncertainty in the values of I0, it is readily explained upon the assumption that a weak excitation produces its full. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original C
Size: 2137px × 1170px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1912
