We study the variation in localized surface plasmon resonance (LSPR) spectra (λLSPR ≈ 600 nm) as a function of dielectric coating thickness. Langmuir−Blodgett multilayers composed of 22-tricosenoic acid (n ≈ 1.53) were deposited onto short-range-ordered Au nanodisks and nanoholes on glass in air. For large dielectric coating thicknesses (d = 100−340 nm), the LSPRs exhibit a pronounced oscillatory behavior with a periodicity of ∼190 nm. This is in agreement with a simple image-dipole model, which yields a periodicity of ∼λLSPR/2n. However, the amplitude of the dipolar plasmon resonance wavelength oscillation λLSPR(d) is surprisingly large, of the order 25−45 nm for d ≈ 300 nm, indicating the importance of finite size effects. The large LSPR shifts observed at such a large distance from the actual metal surface suggest the possibility of using comparatively thick dielectric films as spacer layers in bio/chemo LSPR sensor applications.

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The radio-loud Active Galactic Nuclei (AGNi) having the radio emission arising from a core region rather than from lobes are often referred to as "blazars" and include Flat Spectrum Radio Quasars (FSRQ) and BL Lacertae (BL Lac) objects. We present results of long term observations of FSRQ: among them are known object 3c454.3 (z= 0.859), high-red shifted quasar 1739+522 (4c+51.37) (z= 1.375) and 4c+31.63 (z= 0.295), 4c+55.17 (z= 0.896) as well as BL Lac type object OJ 287 (z= 0.306) that was recently detected by SHALON Cherenkov telescopes. Also, the observation data on known BL Lac objects Mkn 421 (z= 0.031), Mkn 501 (z= 0.034), Mkn 180 (z= 0.046) and Radio galaxies NGC 1275 (z= 0.018), 3c 382 (z= 0.0578) are summarized in this paper. The observation results are presented with integral spectra, images and spectral energy distributions for each of sources at energies above 800 GeV. A number of variability periods in different wavelengths including VHE γ-rays were found.

Abstract. The radio-loud active galactic nuclei having the radio emission arising from a core region rather than from lobes are often referred to as "blazars" and include Flat Spectrum Radio Quasars (FSRQ) and BL Lacertae (BL Lac) objects. During the period 1992 -2015, SHALON has been used for observations of the metagalactic sources NGC1275, Mkn421, Mkn501, Mkn180, 3c382, 4c+31.63, OJ 287, 3c454.3, 4c+55.17, 1739+522. We present results of long term observations of FSRQ: among them are known object 3c454.3, high-red shifted quasar 1739+522 as well as BL Lac type objects. The observation results are presented with integral spectra, images and spectral energy distributions for each of sources at energies > 800 GeV. A number of variability periods in different wavelengths including VHE γ-rays were found. IntroductionHigh and very high energy γ-rays have come to play an important role in the study of Active Galactic Nuclei (AGNi). A big number of AGNi have been detected through the MeV to TeV energies. The long term SHALON observations yielded data on AGNi of different type at energy range of 800GeV -100 TeV (Table 1). The redshifts of AGNi observed by SHALON range from z=0.0179 to z=2.979. Some of these AGNi were discovered at TeV energies by SHALON. The results on fluxes, spectral energy distributions and images are shown here and [1,2,3,4,5].