Supplementary materials
In the studies of SPCE spectroscopy, it is common to achieve a dramatic increase
in the emission intensity compared to the FS emission. However, the event seems
more difficult for SPCE imaging. In previous reports, for gold substrate, the
enhancement of the fluorescence signal in SPCE imaging due to the high
light-collection efficiency is about two fold,1, 2 which is lower than that (about 5 fold)
in RK configuration SPCE spectroscopy.3, 4
We believe that the reason for such a disparity between spectroscopy and
imaging is that the fluorescence signal collected in imaging comes from a wider angle
range than spectroscopy due to the imaging lens. As shown in the Figure S1, a
simulated SPCE intensity curve (red line) for the emission wavelength of 580 nm was
calculated via the Fresnel equation in a four-phase system (BK7 prism/50 nm silver
film/30 nm RhB-PVA film/air). And an ideal FS intensity curve (black line) with
isotropic distribution was used for the discussion. The normalized intensity of FS
(compared to the SPCE peak intensity) was assumed to be 0.1, so the fluorescence
enhancement was 10 fold. The integrated intensities of SPCE and FS with different
angular integration intervals were calculated and shown in Table S1. The intensity
ratios of SPCE to FS (fluorescence enhancement factor) decrease with the increase of
the angular integration intervals. When the angular integration interval is 2°, the
fluorescence enhancement factor reduces to about 3. For imaging, the imaging lens
has a wider angle collection range than spectroscopy which is typically equipped with
a slit.3,4 Therefore, it is more difficult to achieve an exciting fluorescence
enhancement in SPCE imaging than SPCE spectroscopy.
1
Normalized Intensity
1.0
47.94o
0.8
SPCE
FS
0.6
0.4
0.2
0.0
40
45
50
55
60
Angle
Figure S1. Simulated angular distribution of the SPCE intensity (red line) and the
ideal isotropic angular distribution of the FS intensity (black line).
Table S1. The intensity ratios of SPCE to FS with different angular integration
intervals
Angular integration interval
integrated intensity
of SPCE
integrated intensity
of FS
Ratio of SPCE
to FS
SPCE angle 47.94°
1.00
0.10
10.0
0.5°（47.69°~48.19°）
0.39
0.05
7.8
1°（47.44°~48.44°）
0.56
0.10
5.6
1.5°（47.19°~48.69°）
0.63
0.15
4.2
2°（46.94°~48.94°）
0.66
0.20
3.3
2.5°（46.69°~49.19°）
0.68
0.25
2.7
3°（46.44°~49.44°）
0.69
0.30
2.3
Supplementary References
1
J. S. Yuk, M. Trnavsky, C. McDonagh and B. D. MacCraith Biosens Bioelectron 25,
1344 (2010).
2
2
W. P. Cai, Q. Liu, S. H. Cao, Y. H. Weng, X. Q. Liu and Y. Q. Li ChemPhysChem
13, 3848 (2012).
3
C. D. Geddes, I. Gryczynski, J. Malicka, Z. Gryczynski and J. R. Lakowicz J.
Fluoresc. 14, 119 (2004).
4
I. Gryczynski, J. Malicka, Z. Gryczynski and J. R. Lakowicz J. Phys. Chem. B 108,
12568 (2004).
3