Surface-enhanced Raman scattering active gold nanostructure fabricated by photochemical reaction of synchrotron radiation Akinobu Yamaguchi a, * , Takeshi Matsumoto a , Ikuo Okada b , Ikuya Sakurai b , Yuichi Utsumi a a Laboratory of Advance Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205, Japan b Synchrotoron Radiation Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan highlights  Gold nanoparticles were produced by photochemical reaction of synchrotron radiation.  The gold nanoparticles grew and aggregated into the higher-order nanostructure.  The behavior is qualitatively explained by analytical estimation.  The surface-enhanced Raman spectroscopy of 4,4 0 -bipyridine (4bpy) was demonstrated.  The substrate fabricated in a suitable condition provides in situ SERS for 1 nM 4bpy. article info Article history: Received 18 December 2014 Received in revised form 1 April 2015 Accepted 19 April 2015 Available online 23 April 2015 Keywords: Raman spectroscopy and scattering Electrochemical techniques Lithography Nanostructures Optical materials abstract The deposition of gold nanoparticles in an electroplating solution containing gold (I) trisodium disulphite under synchrotron X-ray radiation was investigated. The nanoparticles grew and aggregated into clusters with increasing radiation time. This behavior is explained by evaluating the effect of Derjaguin-Landau- Verweyand-Overbeek (DLVO) interactions combining repulsive electrostatic and attractive van der Waals forces on the particle deposition process. The surface-enhanced Raman scattering (SERS) of 4,4 0 -bipyridine (4bpy) in aqueous solution was measured using gold nanoparticles immobilized on silicon substrates under systematically-varied X-ray exposure. The substrates provided an in situ SERS spectrum for 1 nM 4bpy. This demonstration creates new opportunities for chemical and environmental analyses through simple SERS measurements. © 2015 Published by Elsevier B.V. 1. Introduction Discovered over 30 years ago [1e3], surface enhanced Raman scattering (SERS) is a powerful vibrational spectroscopy technique that has attracted a greater interest in the past decade with the development of nanofabrication, such as nanolithography and nano-imprint technologies [1e 14]. It enables highly sensitive detection of low concentration analytes by amplifying electro- magnetic fields generated by the excitation of localized surface plasmons (LSPs). To this end, gold or silver nanoparticles are typi- cally deposited on nanostructured SERS-active surfaces manufac- tured by photolithography, nano-imprint lithography [10] or electrochemistry [11]. Alternatively, these substrates exhibit an inherent or reactively synthesized nanostructure [12e14]. Various methods have been developed for preparation of SERS- active nanostructures comprising nanoparticles. Chemical ap- proaches [15e17] are noteworthy because they can be modified by external sources, such as sonochemistry [18e21], ultra-violet (UV) irradiation [22,23], as well as X-ray [24e29] oreg ray [30] radiation-assisted chemical reduction. Synchrotron radiation has recently utilized to assist the fabrication of nanoparticles, which have not shown SERS-active properties to date. Ma et al. have re- ported the synchrotron X-ray-enabled synthesis of gold particles on a silicon substrate [24]. Yang et al. [26] and Lee et al. [29] have demonstrated gold and nickel colloidal particles induced by syn- chrotron X-ray radiation. Gold nanoparticles have also prepared using a laboratory X-ray source [28]. Wang et al. have demonstrated the one-pot synthesis of AuPt alloyed nanoparticles under intense * Corresponding author. E-mail address: yamaguti@lasti.u-hyogo.ac.jp (A. Yamaguchi). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys http://dx.doi.org/10.1016/j.matchemphys.2015.04.025 0254-0584/© 2015 Published by Elsevier B.V. Materials Chemistry and Physics 160 (2015) 205e211