Dispersive surface plasmon microscopy for the characterization of ultrathin organic films

Abstract

We report on experiments, applying a novel microscopy method for ultrathin-film characterization which uses the dispersion properties of plasmon surface polaritons (PSP) as a contrast giving mechanism. In contrast to prior methods, we apply white light instead of a laser for resonant PSP excitation. For a given incident angle and an area of given thickness, a narrow spectral band of the incident light is at resonance for PSP excitation. Therefore, we obtain images with areas of different thickness appearing in different color. As an example, we present microscopic images taken from a thin Cu–phthalocyanine film, evaporated onto solid support through a mask. In addition, we compare the obtained images to theoretical considerations on the contrast mechanism.

Near-Infrared Surface Plasmon Resonance Measurements of Ultrathin Films. 1. Angle Shift and SPR Imaging Experiments

“…SPR imaging with an incoherent white light source has been demonstrated previously where changes in color due to SPPs were used to image a patterned substrate in the visible region. 24 The addition of the band-pass filter allows for easy selectivity of the imaging wavelength and allows for the use of a simple CCD camera. Sharper SPR reflectivity curves in the NIR mean better image contrast compared to that in the visible region and less manipulation to find the best angle for the SPR imaging measurement.…”

“…Different wavelengths can also be employed in the SPR imaging experiment; one previous study employed broad-band visible illumination for the SPR imaging of copper phthalocyanine thin films. 24 In this paper, we demonstrate the benefits of using NIR light for SPR angle shift and SPR imaging measurements. As can be seen in Figure 1, use of NIR excitation in SPR scanning angle experiments changes the position and sharpness of the SPR angle.…”

“…For example, SPR angle shift measurements have been made previously in the near-infrared (NIR) out to 3.39 μm. ,− For cases where the adsorbing molecules have a strong absorption band in the visible region, the analysis of SPR angle shift measurements can be simplified by using NIR excitation. Different wavelengths can also be employed in the SPR imaging experiment; one previous study employed broad-band visible illumination for the SPR imaging of copper phthalocyanine thin films …”

Analysis of immunoarrays using a gold grating-based dual mode surface plasmon-coupled emission (SPCE) sensor chip

“…Grating pitch and optical properties such as refractive index and excitation wavelength also significantly affect the SPR response. [17][18][19][20] The grating vector G decreases increasing pitch size and the wave vector k x of the incident light increases as the angle of incidence increases, although k sp of the surface plasmon does not change with pitch size or angle of incidence. According to the resonance condition of eqn (3), the diffracted wave vector should match the wave vector k sp of the surface plasmon, and thus surface plasmons on the longer pitch grating surface are excited by light at a larger incident angle.…”

Study on conditions of DNA immobilization by surface plasmon resonance imaging

“…However, the SPR imaging sensors currently in use have their drawbacks. Some sensors such as SPM [4] have a narrow linear range and offer only qualitative results [4][5]. The ones which can provide qualitative data suffer different shortcomings such as a low resolution [6]or a time-consuming sensing speed [7].…”