Optical spectroscopy provides non‐invasive, in‐situ, real time (and sometimes femtosecond time‐resolved) probing of surfaces and buried interfaces over macroscopic areas, features that complement atomic‐scale probes such as scanning‐tunneling microscopy. Since its inception back in 1995, the International Conference on Optics of Surfaces and Interfaces (OSI) has included cutting‐edge experimental and theoretical work in ellipsometry, reflectance‐anisotropy spectroscopy, magneto‐optics, Raman scattering and surface second‐harmonic generation. More recent OSI conferences have also featured work on optical methods that resolve sub‐wavelength structures, plasmonics, organic and biological interfaces, optics of nanostructures, graphene‐like surfaces including transition metal dichalcogenides, meta‐surfaces and single nano‐objects. An emerging field of metamaterials applied to subwavelength optical devices is now present in the OSI plethora of topics.

The seven peer‐reviewed papers in this special section of physica status solidi (b) represent examples of both traditional and emerging OSI themes, as discussed at the 13^th International Conference on Optics of Surfaces and Interfaces (OSI‐13), and include both theoretical and experimental work. A wider range of topics may be found in the conference presentations, available from within the talks schedule at the OSI‐13 website: http://congresos.cio.mx/OSI_2019/.

OSI‐13 was held in the Center for Optical Research (CIO), León, México, from June 3–7, 2019, organised by Bernardo Mendoza, Ramón Carriles, Sean Anderson and Norberto Arzate. This is the second time that OSI has been organized at the CIO. The OSI conference is held biennially and started in Rome in 1995. Subsequent conferences were held in Åalesund (Norway), Sainte‐Maxime (France), Bad Honnef (Germany), León (México), Aalborg (Denmark), Grand Targee (USA), Ischia (Italy), Akumal (México), Chemnitz (Germany), Austin (USA), lastly, in Dublin (Ireland) in 2017. The conference has alternated between Europe and the Americas since 2001, reflecting its international profile. OSI‐14 will be held in Raleigh, North Carolina, USA in 2021.

光谱学提供了对宏观区域表面和掩埋界面的非侵入性，原位实时（有时是飞秒时间分辨）探测，这些特征补充了原子尺度探针，例如扫描隧道显微镜。自1995年成立以来，国际表面和界面光学大会（OSI）一直在椭圆偏振，反射各向异性光谱，磁光，拉曼散射和表面次谐波产生领域进行前沿的实验和理论研究。最近的OSI会议还重点讨论了解决亚波长结构，等离激元，有机和生物界面，纳米结构的光学，包括过渡金属二卤化物在内的石墨烯表面，超表面和单个纳米物体的光学方法。

在第13^届国际表面与界面光学会议（OSI-13）上讨论的，在这一物理状态特别部分（b）中的7篇经过同行评审的论文代表了传统和新兴OSI主题的示例。理论和实验工作。在会议演讲中可以找到更广泛的主题，可以从OSI-13网站的演讲时间表中获取：http://congresos.cio.mx/OSI_2019/。

OSI-13于2019年6月3日至7日在墨西哥莱昂光学研究中心（CIO）举行，该中心由Bernardo Mendoza，RamónCarriles，Sean Anderson和Norberto Arzate组织。这是OSI第二次在CIO上进行组织。OSI会议每两年举行一次，于1995年在罗马开始。随后的会议分别在Åalesund（挪威），Sainte-Maxime（法国），Bad Honnef（德国），León（墨西哥），Aalborg（丹麦），Grand Targee（美国）举行。 ），伊斯基亚（意大利），艾库玛尔（墨西哥），开姆尼茨（德国），奥斯汀（美国），最后于2017年在都柏林（爱尔兰）。该会议自2001年以来在欧洲和美洲之间交替举行，反映了其国际知名度。OSI-14将于2021年在美国北卡罗来纳州罗利举行。