1. 中國科學院 重慶綠色智能技術研究院 Zhongbo Yang等

Near-Field Nanoscopic Terahertz Imaging of Single Proteins. Small.

Figure 1. Schematic illustration of the THz s-SNOM setup and its   use for single biomolecule imaging.

Figure 2. THz   near-field signals collected on different substrates. a) Time-domain THz   electric field signals, and b) corresponding frequency-domain signals   collected on graphene, Au, Si, and mica surfaces, respectively. The signals   were demodulated at the second harmonics (2 Ω) of the   probe oscillation frequency. c,d) The AFM topography images of graphene and   Au substrates with 200 × 200 pixels, respectively. The height scale bars of (c)   and (d) are the same.

摘要：太赫茲生物成像因其能以無標記、無創傷和非電離的方式獲取樣品的物理化學信息而頗受矚目。但是，低介電常數生物分子的反射率問題，使得單分子精度的太赫茲成像仍是個挑戰。針對于此，作者開發了種方法，用石墨烯介導的太赫茲頻率散射型掃描近場光學顯微鏡，對單個蛋白分子直接成像。此項研究發現，擁有較高太赫茲反射率和原子平整度的石墨烯基底可以為蛋白分子提供較高的太赫茲對比度。另外，我們還發現對鉑探針的軸長化能增強太赫茲散射近場信號中的振幅信號強度。基于這兩個效應，作者同時獲得了尺寸只有數納米的免疫球蛋白G（IgG）和鐵蛋白分子的形貌以及太赫茲散射圖像。本文中所用的方法為單生物分子的太赫茲成像提供了新思路。

2. 華中科技大學 Chao Chen等

Terahertz Nanoimaging and Nanospectroscopy of Chalcogenide Phase-Change Materials. ACS Photonics 2020.

Figure 2. THz   near-field setup and imaging experiments. (a) Schematics of the THz s-SNOM   setup with a bolometer used as a detector. The inset shows an illustration of   the finite dipole model for the layered sample. (b) Approach curve, showing   the amplitude signal s2 on c-GST as a function of tip–sample distance. The   mark h1/e represents the position at which the signal decays to 1/e of its   maximum. The inset displays an optical microscope image of the AFM tip above   the sample. The red dotted squares mark the c-GST areas. (c) AFM topography   image (top panel) of GST on a silicon oxide substrate, which includes   amorphous and crystalline states. Near-field amplitude (s2, middle panel) and   phase (φ2, bottom panel) images at 1.89 THz. (d) Topography, (e) near-field   amplitude, and (f) phase line profiles (shown as solid symbols) taken from   the corresponding images in c. The red solid lines are smoothed curves based   on the experimental data. Horizontal dashed gray lines are a guide for the   eye.

摘要：硫屬化物相變材料（PCMs）在太赫茲（THz）頻率下會發生光學聲子共振現象，這個效應可被用于研究相變的基本性，并產生很強的介電對比度，使其可被用于太赫茲的光子學應用。在本文中，我們證明可以通過頻率可調的太赫茲散射型掃描近場光學顯微鏡（s-SNOM）研究PCM的聲子。其具體方法為對包含非晶相和結晶相的PCM樣品進行太赫茲納米光譜成像。我們觀察到材料的聲子征使其產生了很強的s-SNOM信號，以及重要的是，非晶態和結晶態PCM的光譜之間存在明顯的差異，這使我們可以在納米尺度上高信度地區分PCM的不同相。我們還發現可以通過增加針尖的半徑來增強以信號強度和頻譜對比度為標志的光譜征。綜上所述，我們用太赫茲s-SNOM成功構建了基于局部聲子光譜的納米結構以及化學組成的圖譜。

3. 中國地質大學-武漢 Zhigao Dai等人

Edge-oriented and steerable hyperbolic polaritons in anisotropic van der Waals nanocavities. Nat. Commun..

Figure 1.   a Schematic   diagram of edge-tailored PhPs in α-MoO₃. The edge orientation is   defined as angle θ with respect to the [001] direction. Green arrows indicate   the incident PhPs waves launched by the laser-illuminated (purple curve arrows) AFM tip and reflected by the edge (red line). b Angle-dependent ke isofrequency   contour of PhPs in α-MoO₃ at ω?=?889.8?cm^?1.   The solid lines and points stand for experimental results concluded from   Fig. 1c. The green and black dotted arrows   illustrate the incidence wavevector ki and   Poynting vector Si, respectively. Generally, ki and Si are   non-collinear. The reflected Poynting vector Se (solid   arrows) is not parallel to the reflected wavevector ke (different   color solid arrows) but antiparallel to Si. σ is   the open angle. c Real-space imaging of edge-tailoring PhPs   at angle-dependent α-MoO₃ edges (length L: 2.5?µm; width W: 200?nm; sample thickness d: 210?nm, L and W defined in the Ed1). d s-SNOM   line traces along the direction perpendicular to the edges in Ed1-Ed5. e Near-field   amplitude s(ω) of PhPs on isosceles triangle α-MoO₃ nanocavities   with bottom edge perpendicular to the [001] crystal direction (height length: 4.33?μm; thickness: d?=?175?nm); The angles between adjacent   sides of the series of triangles with respect to the [001] direction are   approximately 7.5°, 15°, 30°, 45°, and 60°, respectively.

摘要：高度受限和低損耗的化子在石墨烯和六方氮化硼上是沿平面各向同性傳播的，這使得對光的控制被限制在了有限的自由度內。而以α-MoO₃ and V₂O₅為代表的新興雙軸范德華材料則展現出了*的化傳播性，它們的輔助光軸是在平面上的。用這種強平面各向異性，作者通過空間納米成像觀測到了α-MoO₃納米腔的圖樣內有著受邊界導向的雙曲化子。并且發現邊界的夾角和結晶方向對其光學響應信號有著*的影響，這對調整化圖樣的參數是至關重要的。基于此，通過調整α-MoO₃納米腔的幾何構型，我們觀測到了雙曲化子會延邊界傳播并且會調整自身傳播方向的性以及與之對應的化子繞行禁·區。而這種雙曲化子的壽命和性能指數則受到納米腔邊界寬高比的限制。

4. 國防科學技術大學 Jiangyu Zhang 等人

Light-induced irreversible structural phase transition in trilayer graphene. Sci. & App..

Figure 4. Raman   mapping and s-SNOM imaging of the light-induced structural phase transition   in MLG. (a) Optical   microscopy image of MLG sample #125. (b) AFM image and height   profile of graphene. (c) Raman maps of the integrated G peak   intensity (position: 1576?cm^?1, width: 5?cm^?1) before   laser irradiation and (d) after laser irradiation. The laser power is 20?mW,   and the exposure time is 34?min. (e) s-SNOM image of graphene after   laser irradiation. (f) Magnified s-SNOM image of graphene. Graphene   domains with different stacking orders show different contrasts in the s-SNOM   image. The marked regions I, II, and III correspond to ABC stacking, ABA   stacking and mixed ABC?+?ABA stacking domains, respectively. The red arrows   in (e, f) highlight the additional mixed ABC?+?ABA stacking domains that   were not resolved in the Raman maps. (g) Raman spectra of different   graphene regions taken from the marked solid dots before laser irradiation   and (h) after laser irradiation

摘要：晶體結構對相關材料的物理性質有著深刻的影響。因此，即使化學組成相同（比如石墨烯和金剛石），我們也可以通過生成具有定對稱性的晶體，來很大范圍內調整它們的性。而當晶體的結構相可以通過外部刺激動態改變時，更多有意思的可能性出現在了我們面前。這樣的材料性雖不常見，但卻能引發很多喜人的現象，例如相變記憶效應。具體到三層石墨烯，它有兩種常見的堆疊結構（ABA和ABC），二者都具有*的電子能帶結構，并展現出了與眾不同的性。而這兩種堆疊結構的三層石墨烯里的疇壁，則展現出了新的迷人的物理效應，比如說量子谷霍爾效應。科研工作者在三層石墨烯的相工程上投入了大量的精力。不過，操縱疇壁以實現對材料局部結構和性的精準調控仍然是個難題。本文通過實驗表明，通過激光照射可以實現結構相之間的轉換，并在三層石墨烯中構建各種形狀的疇壁。這種能夠控制疇壁位置和方向的能力，使得我們能夠更好地調整石墨烯的局部結構相和性，并為可定制原子結構，電子以及光學性的人造二維材料的生成提供了種簡潔且有效的路徑。

5.  華中科技大學 Peining Li等人

Collective near-field coupling and nonlocal phenomena in infrared-phononic metasurfaces for nano-light canalization. Nat.Commun..

Figure 2. Near-field imaging of polariton evolution in   a hBN metasurface. a Schematic of the near-field nanoimaging   experiment. b, c Near-field images measured at two different   frequencies, ω?=?1415?cm^?1 (HPhP region)   and ω?=?1510?cm^?1 (EPhP region). White arrows   indicate the polariton fringes observed on the metasurface.

摘要：通過光子耦合激發和偶物質激發所產生的化子可以沿具有雙曲線色散或橢圓色散的各向異性超表面傳播。而在雙曲線色散與橢圓色散之間的轉換過程中（對應拓撲結構的轉換），有各種有趣的現象被觀測到，比如光子態密度的增強、化子的溝道效應和超透鏡效應。在本文中，作者從理論角度和實驗角度分別研究了這種拓撲結構的轉換，單軸紅外聲子超表面中的化耦合和其強烈的非局域響應信號，以及六方氮化硼 (hBN) 納米帶的光柵。 通過超高分辨紅外10納米成像，研究者觀察到了六方氮化硼中余輝帶里合成的橫向光學聲子的共振（即納米帶強烈的集體性近場耦合），這觸發了從雙曲線色散向橢圓色散的拓撲轉換。作者還表征并可視化了躍遷頻率附近深亞波長通道模式的空間演化，該模式作為種準直化子為超透鏡和無衍射傳播打下了基礎。

6. 山西大學 PengjuYang 等人

Rational electronic control of carbon dioxide reduction over cobalt oxide. J. Cat..

Figure 2. (a) XPS Co 2p of Co₃O₄ and   Co₃O₄/Al-1(1 wt% Co₃O₄), (b)   XPS Al 2p of Co₃O₄/Al-1 and Al-1, (c-d) the S-SNOM   optical image of Co₃O₄/Al-1(1 wt% Co₃O₄)   and SNOM amplitude S3 of lines A-E.

摘要：選擇性地將二氧化碳(CO₂)還原為燃料和化學品是通過碳中和發展可持續性能源經濟的重點所在。而其中CO₂的活化則是重中之重。考慮到電子遷移是這過程的決速步驟，通過調節CO₂還原催化劑的電子結構來增強其活性則顯得更為關鍵。不過，人們對催化劑的電子性與活性的內在關系的理解還不是很深入，這也限制了高效CO₂還原催化劑的有理論支撐的設計。本文中，作者設計了種以鋁作為電子供體的催化劑-緣體-金屬系統，并以此來調節氧化鈷(Co₃O₄)催化劑的電子結構。這樣，鋁中的電子便可以高效地通過種超薄且自主形成的Al₂O₃緣層穿入Co₃O₄。實驗和理論結果毫無疑問確證了Co₃O₄的高電子密度有于CO₂的吸收和活化，并同時降低了COOH的生成能壘，尤其是CO*中間體的解吸能壘，這大大加速了CO₂到CO的光還原反應的動力學進程。相比Co₃O₄，Co₃O₄/Al₂O₃-Al中的Co的周轉頻率要高出很多。其表觀量子產率在420納米處能高達3.8%，這數字超越了大部分文獻中對催化劑的記述。另外，Co₃O₄ 中電子密度的提高也有效地抑制了析氫競相反應。同時對CO的篩選性也從Co₃O₄的57.9%提高到了Co₃O₄/Al₂O₃-Al的82.4%。值得注意的是，通過控制Al的含量和粒徑我們還可以合理調節催化劑的催化效率。綜上，該項研究建立了催化劑的電子結構與其對 CO₂ 還原反應的催化活性之間的聯系。并且，作者提出的這種Al₂O₃-Al結構，還有潛力成為其他非均相催化劑電子效應研究的全新平臺。

7. 中山大學 Yan Shen等人

Pyramid-Shaped Single-Crystalline Nanostructure of Molybdenum with Excellent Mechanical, Electrical, and Optical Properties. ACS Appl. Mater. Interfaces.

Figure 6. Optical properties   of the pyramid-shaped single-crystalline Mo nanostructures. (a, b) AFM   topography and the corresponding optical near–field amplitude (third   harmonics, at excitation of 633 nm) images of a typical individual,   respectively; the insets are the structural models that help to understand   this sample’s geometric features.

摘要：定的幾何形貌與改進過的晶體性對微納米尺度材料的開發來說是*的。不過，對于高熔點鉬來說，想高質量地生成同時具有單晶性和預設形貌的結構是很困難的。在本文中，作者通過種熱蒸發技術和與之對應的實驗調控，生成了金字塔形的單晶結構鉬。而之后細致的材料表征工作則表明其生長機理遵循的是個包括MoO₂分解、Mo 沉積、島狀單晶形成、層狀成核和競爭性生長在內的連續性過程。此外，經測量還發現這種生成物有著非常秀的物理性能。比如通過機械性能的測量，發現納米結構的鉬展現出了遠高于其塊體材料的納米壓痕硬度、彈性模量和拉伸強度。而在電子性的測量中，這種材料的單體結構則展現出了非常秀的電傳輸性，其電導能達到約0.16 S。所制備的0.02平方厘米的膜材料展現出了大電流電子發射性，其大電流達到了33.6毫安，其電流密度則達到了1.68安每平方厘米。同時，通過光學性的測量，該團隊發現這種結構展現了明顯的電磁場定位和增強效應，這使其作為基底材料，非常適合應用于表面增強拉曼散射（SERS）。作者還進步討論了對應的結構與響應信號之間的關系。文章中提到的，包括微納米尺度，每個晶粒中所蘊含的單晶性，以及材料的金字塔尖形貌在內的，這些納米結構鉬的基礎性，都對其物理性有著正面的影響。

8. 香港理工大學 Xin Hu等人

Infrared Nanoimaging of Surface Plasmons in Type-II Dirac Semimetal PtTe2 Nanoribbons. ACS Nano..

Figure 6. Near-field images and plasmonic properties of sub-10 nm PtTe₂ tapers.   (a) Topography of the PtTe₂ taper (NT1) with a thickness of   10.4 nm. The inset is the height profile along the white dashed line. (b)   Experimental near-field image of NT1 at the laser frequency of 2500 cm^–1 (λ₀ = 4 μm). (c) Simulated image of the near-field standing-wave pattern   corresponding to (b). The standing-wave patterns in the PtTe₂ tapers   are mimicked by E_nf = E₀ + r₁ exp(2ik_sp·x₁) + r₂ exp(2ik_sp·x₂), where x₁ and x₂ are   the perpendicular distances from an arbitrary point in the taper to its two   edges. The propagation constant k_sp = (2.264 +   0.884i)k₀, supposing the permittivity of the 10.4 nm   PtTe₂ film is identical to the bulk permittivity, and E₀ =   1, r₁ = r₂ = 0.2. (d)   Topography of NT₂ with a thickness of 5–7 nm. The inset is the height profile   along the black dashed line. (e) Near-field optical image of NT₂ at the laser   frequency of 1400 cm_–1 (λ₀ = 7.14 μm). (f)   Near-field optical image of NT₂ at the laser frequency of 2500 cm^–1.   The domains in NT₂ have different layers (L) ranging from 10L (～5 nm) to 13L (～7 nm). All scale bars are 1 μm.

摘要：由二維過渡金屬二硫屬化物制成的拓撲狄拉克半金屬(TMDCs)，因其電子傳輸性，在電子和光電設備域的應用得到了廣泛的關注。作為具有強層間相互作用的范德華材料，這種半金屬被期望可以用于支持尚未被實驗證明的層相關等離子體化激元的存在。在本研究中，作者用近場納米成像展示了II型鉑碲狄拉克半金屬（PtTe-₂）納米帶和納米薄片中的中紅外等離子體波的延遲和衰減。從近場駐波圖像中總結出的PtTe-₂納米帶（厚度為15到25納米）的等離子體模式衰減色散關系被應用于MIR區的PtTe-₂介電常數擬合，其結果表明自由載流子和狄拉克費米子都參與了中紅外光和物質的相互作用。而對超薄（小于10納米）PtTe_-2等離子體模式的湮滅的觀察和分析使作者發現是PtTe-₂與本征層相關的光電性導致了其無近場共振圖像的現象。以上結果為應用TMDC進行MIR區的光電探測和調制鋪展了道路。

9.     上海微系統所&長春光機所 Weiliang Ma等人

Broad spectral tuning of ultra-low-loss polaritons in a van der Waals crystal by intercalation. Nat. Mater..

Figure 2.   a–c, Near-field   amplitude images s₃ of an α-V₂O₅ flake   with thickness d?=?105?nm at incident frequencies ω₀?=?1,031   (a), 1,026 (b) and 1,020?cm^?1 (c). Scale   bar in c, 2?μm. d–f, Profiles along the [100]   (green lines) and [001] (blue lines) directions, extracted from the   near-field amplitude images in a–c, respectively. λp[100] and λp[001] are   the polariton wavelengths along the [100] and [001] directions,   respectively. g, Dispersion of PhPs along the [100] (green   symbols) and [001] (blue symbols) directions in the RB1. Grey   lines are guides for the eye. Grey shaded areas indicate the spectral regions   outside the RB. a.u., arbitrary units.

Figure 3.   a, Illustration of the   α-V₂O₅ lattice structure (orthorhombic) where the   red spheres represent oxygen atoms, the blue atoms represent vanadium atoms,   and the blue pyramids show the polyhedral structure defined by the oxygen   atoms. The crystal structure consists of bilayers of distorted VO₅ pyramids   stacked along the [010] direction via vdW interactions (interlayer   distance c?=?0.44?nm). b, nanoFTIR spectral line   scans along the [100] and [001] directions of a α-V₂O₅ flake   showing s₃/s₃, Au (near-field amplitude s₃ normalized   on Au, s₃,Au) as a function of distance between the tip and the   flake edge. Solid horizontal lines mark the approximate transversal optic   (TO) phonon modes in α-V₂O₅ (TO₁, 975?cm^?1; TO₂, 770?cm^?1), separating RB_1–3. Dashed lines are guides for the eye of signal maxima. The flake thickness   is d?=?245?nm. c, Illustration of the α’-(Na)V₂O₅ lattice   structure (orthorhombic) where the red spheres represent oxygen atoms, the   blue atoms represent vanadium atoms, the yellow atoms represent sodium atoms   and the blue pyramids show the polyhedral structure defined by the oxygen   atoms. The crystal structure consists of bilayers of distorted VO₅ pyramids   with sodium atoms intercalated and stacked along the [010] direction via vdW   interactions (interlayer distance c?=?0.48?nm). d,   nanoFTIR spectral line scans along the [100] and [001] directions of a   α’-(Na)V₂O₅ flake showing s₃/s₃, Au (near-field   amplitude s₃ normalized on Au, s₃,Au) as a   function of distance between the tip and the flake edge. The solid horizontal   line approximately mark the transversal optic phonon mode in α’-(Na)V₂O₅ (TO,   950?cm^?1), defining RB’1. The flake thickness is d?=?150?nm.   The scales in the colour bars of b and d are   linear.

摘要：性范德華晶體中的聲子化子——種光與晶格振動的耦合——是有在納米尺度上控制能量流動的有力候選者，因為它們有著很強的限制場、各向異性的傳播方式和皮秒的超長壽命。不過，它們狹窄且只適用定材料的光譜響應范圍——也就是剩余射線帶——大地限制了其技術應用。在此，在α-V₂O₅范德華半導體中嵌入鈉原子，能增寬其剩余射線帶，并因此讓受激聲子化子展現出低的損耗率（壽命為4±?1皮秒），這個數值已經與其在非插層晶體（壽命為6±?1皮秒）中的表現相近。作者預計這種嵌入方法也能被應用于其他范德華晶體，從而提供種新的用聲子化子增寬中紅外區域頻譜的方法。

10.  中國科學技術大學 Xinzhong Chen

Moiré engineering of electronic phenomena in correlated oxides. Nat. Phys..

Figure 3. a,b,   Infrared near-field image of a curved moiré pattern (a) and the corresponding   simulation (b). The simulation is generated by multiplying two periodic   striped patterns representing MSs and DSs. The white and black dashed lines   in b indicate the MS and DS orientations, respectively. c, Line profiles from the blue dashed lines in a and b, exhibiting high consistency between the experimental and the simulated   contrast. a.u., arbitrary units. d,e, Infrared near-field image and   corresponding AFM image, respectively, showing alternating moiré and   non-moiré regions across the LAO twin boundaries (indicated by red dashed   lines). The white solid line in e is the AFM height   profile. f, Line profile of the nano-infrared contrast along the blue   dashed line in d. The different signal levels are marked ‘C’, ‘D’ and   ‘M’, which represent constructively strained, destructively strained and   mixed strained regions, respectively. g, Simulation of the image   in d with the moiré pattern only visible on the right-hand side.   Note that the MSs (orientation indicated by white dashed lines) change   orientation across the LAO twin boundary (red dashed line), while the DSs   (orientation indicated by black dashed lines) are consistently along the LAO [100] direction. The simulation details are shown in Extended Data Fig. 8c.

摘要：近段時間，摩爾紋工程被視為控制凝聚態系統中量子現象的有效途徑。在范德華異質結構中，莫爾紋可以通過相鄰原子層之間的晶格錯位形成，并因此產生長程電子有序的結構。到目前為止，摩爾工程只在堆疊范德華多層結構上有所應用。而在本文中，作者描述了種在LaAlO₃基底上外延生長的原型性磁阻氧化物薄膜La_0.67Sr_0.33MnO₃中產生的電子摩爾紋。通過掃描探針納米成像，作者觀察到了薄膜中應變調制的兩種不同的非公度紋的共存和互相影響所產生的微觀摩爾紋。其凈效應表現為La_0.67Sr_0.33MnO₃的電子電導率和鐵磁性直到細觀尺度都會受周期性摩爾紋的調制。我該研究工作為在應力外延材料中獲得定制的電子紋理的空間圖樣開辟了條潛在的道路。

11.  國家納米中心 Xiangdong Guo

Efficient All-Optical Plasmonic Modulators with Atomically Thin Van Der Waals Heterostructures. Adv. Mater..

Figure 2. The all-optical graphene plasmon waveguide   modulation with a thickness of only several atomic layers. a) Schematic   diagram of band alignment and the physical mechanism of photocarrier transfer   in the hole-doped graphene/MoS₂ heterostructure under visible light irradiation. b,c) Near-field images of a graphene/MoS₂ heterostructure on SiO₂ substrate in the b) absence and c) presence of 633 nm laser irradiation (6 mW cm^?2). Dashed lines indicate the graphene edge. d) The   plasmon signals extracted from the cut-lines (red and blue lines) in (b) and   (c), respectively.

摘要：全光調制器正越來越受矚目，這主要是因為它高速度，低損耗，與高帶寬的本征性，使其在未來的信息通訊技術中可以很好地為對應的電氣元件做更新換代。但是，其較大的能量消耗與尺寸使得其光子間相互作用較弱，從而阻礙了其在非線性光學上的廣泛應用。在本文中，作者通過在石墨烯中摻雜含有光生載流子的單層MoS₂生成了原子薄度石墨烯-MoS₂異質結構，形成了種高效全光中紅外等離子體波導和自由空間調制器。44 cm^-1等離子的調制也通過LED得以呈現，其光強度可以低達0.15 mWcm^-1,這數值比通用的石墨烯非線性全光調制器要低4個數量（≈103 mWcm^-2）。異質結構中光生載流子的超高速遷移以及復合的速率使得石墨烯等離子體的超高速調制成為了可能。作者認為，基于范德華異質結構的帶有芯片可集成性和深亞波長光場限制性的高效全光中紅外等離子體調制器的開發或許向片上全光器件應用的實現邁出了重要的步。

12.  華中科技大學 Peining Li等人

Nanoscale Guiding of Infrared Light with Hyperbolic Volume and Surface Polaritons in van der Waals Material Ribbons. Adv. Mater..

Figure 4. Thickness dependence of h-BN waveguide modes.   a) Schematics of the experiment. b) Near-field amplitude images s₃ of h-BN waveguides of same nominal width w = 1 µm and different   thicknesses d at ω = 1430 cm^?1. c) Wavevector of the waveguide modes as a function of thickness. Symbols indicate experimental wavevectors measured at the edge (triangles) and at the   center (circles) of the waveguide. The solid and dashed lines show   wavevectors obtained with the full-wave simulations. The dotted red line is a   guide to the eye. The inset shows line profiles from 16 nm thick waveguide at   edge (gray) and center (blue) as indicated by arrows in (b). d) Schematic comparison   of dielectric and hyperbolic volume waveguide modes near cutoff, when the   thickness of the waveguide is decreased.

摘要：范德華（vdW）材料因其所含有的各種化子，成為了新興的納米尺度光操縱用材料平臺。憑借范德華材料的層狀結構，這些化子在薄片當中呈雙曲線色散和納米體制御模式。另方面，它們在薄片邊緣則呈面制御模式。然而令人意想不到的是，這些模式在以典型的線性波導結構為代表的帶狀材料上的導向正全·方位地亟待研究。作者就六方氮化硼帶中雙曲聲子化子的傳播方式的研究成果做了詳細的報告。通過納米紅外成像，作者觀測到了各種模式。尤其是展現出截止寬度的重要的體波導模式。并且有趣的是該截止寬度可以通過降低波導厚度來減小。除此之外，該團隊還觀察到了具有不同頻率和波導寬度的面模式雜化以及演化。而重點是，作者發現對稱雜化面模式并沒有展現出任何截止寬度，這讓任意窄帶里的化子都呈線性波導。另外，研究者的實驗數據也支持了相關的模擬結果，這為我們在未來的光子器件應用中擔當重任的線性波導雙曲化子的理解打下了堅實的基礎。

13.  清華大學 Shuai Wu等

Super-Slippery Degraded Black Phosphorus/ Silicon Dioxide Interface. ACS Appl. Mater. Interfaces.

Figure 3. Chemical structure of the BP/SiO₂ interface.   (a) AFM amplitude image and (b) phase image (scale bars: 2 μm) after the   motion of the degraded BP flake on the SiO₂ substrate. (c)   Normalized nano-FTIR phase (φ) spectroscopy plots of the degraded BP surface,   residuals on the substrate, and fresh BP flake (exfoliated within 30 min) in   the region of 900–1100 cm^–1. (d) {¹H-³¹P}¹H   double CP spectra of the BP/SiO₂ sample; the first contact   time (t_CP1) was set to 5 ms, and the variable second   contact time (t_CP2) is indicated on each spectrum.

摘要：二維（2D）材料與二氧化硅（SiO₂）/硅（Si）基底之間的界面，通常被看做是固固機械接觸。這在微系統和納米工程的結構設計與性能化時，常常會被別強調。不過，如何理解基于2D材料的系統的界面結構與動力學仍然是個懸而未決又無法繞過的問題。在本研究中，由于在常態降解時引入了羥基，層在界面內可流動的水被插入了降解黑鱗（BP）薄片與SiO₂/Si基底之間。因此，作者得到了個滑度*的降解BP/SiO₂界面。通過實驗測定，其界面剪切應力（ISS）可低達0.029 ± 0.004 MPa，這數值已可與非公度剛性晶體接觸*。通過分析核磁共振波譜儀和原位X射線光電子能譜儀進行的結果，該團隊發現界面內的液態水的存在是剪切應力低的超高滑度BP/SiO₂界面的形成主因。這發現證明了降解BP和水分子之間存在著強烈的互相影響，并表明納米BP膜在生物基潤滑域有著廣泛的應用潛力。

14.  北京理工大學 Tao Yan等人

Facile preparation and synergetic energy releasing of nano-Al@RDX@Viton hollow microspheres. Chem. Eng. J..

Figure 4. Topography (a) and near-field amplitude   image of the microsphere at frequency ω?=?923?cm^?1 (b),   1131?cm^?1 (c) and 1168?cm^?1 (d). Line   profiles of infrared signal extracted at the position indicated by the red   dashed line (e).

摘要：為了提高含能材料的反應速率，電噴霧技術被應用于雙溶劑法集成納米鋁（nAl）和氟橡膠（Viton）的重結晶環三亞甲基三硝胺 (RDX)微球的開發。其形貌征與化學異質性的測試結果表明電噴霧生成的微球是空心的，并有RDX均勻地分布在其中。而且RDX的納米晶體是緊密地附著在nAl@Viton骨架的兩側的，這增大了不同組分之間的接觸面積。另方面，對微球的熱分析則表明，通過減小微球分解的表觀活化能，nAl顆粒能夠加速能量的釋放。實驗結果表明電噴霧nAl@RDX@Viton，因其各組分的征結構和協同作用，比物理混合物具有更短的激光點火延遲和更劇烈的燃燒火焰。

15.  上海光機所 Lulu Chen等人

Near-field imaging of the multi-resonant mode induced broadband tunable metamaterial Absorber. RSC Adv..

Figure 5. (a)   Experimental absorptivity of the GST absorber between two states. The black   line and red line are for the a-GST and c-GST sample. (b) The simulated spectra for the total and each layer of the c-GST absorber. Inset: the magnetic field distribution at the resonance wavelength. (c–f) Experimental and simulated   near-field amplitude |E_z| and phase φ_z images   mapped at the spectral positions C and C₁.

摘要：具有可調性的超材料吸收器在中紅外吸收的應用域具有廣闊的前景。雖然研究者們提出了各種控制吸收的方法，如何深入分析和呈現吸收機制的物理圖像仍是值得期待且有意義的。在本文中，作者用近場光學顯微鏡展示了多諧振模式誘導下的帶寬可調超材料吸收器的實驗空間近場分布。該吸收器由雙倍尺寸的單元結構與金屬鏡片構成，二者由Ge₂Sb₂Te₅ (GST)薄墊片加以分割。為了獲得清晰的物理圖像，作者用由四個方形諧振器組成的混合單元結構，在 7.8 μm 和 8.3 μm 處產生兩個吸收峰。當GST薄膜從非晶態轉變為晶態時，共振的中心波長呈現紅移趨勢。而無論GST處于那種相態，我們都分別在其吸收頻率下觀察到了吸收器產生的近場振幅和相位的光學信號。綜上，本研究為光學可調吸收的控制打下了科學理論的基礎，并展現了其潛在的應用前景。

16.  中國科學技術大學 Wenhao Zhang and Yuhang Chen

Visibility of subsurface nanostructures  in scattering-type scanning near-field optical microscopy imaging. Opt. Expr..

Figure 1. (a)   Schematic illustration of the experimental s-SNOM setup for investigating the   visibility of buried structures in a multilayered architecture. The   underneath structures are patterned on a metal film and they are covered with a thin polymer layer. A pseudoheterodyne detection method is employed to obtain background-free near-field optical signal. (b) Schematic illustration of the dipole model for a simple theoretical analysis.

Figure 7. Subsurface nano-imaging by s-SNOM. The sample is a   patterned silicon substrate covered by the glue from a double-side tape. (a)   Topography. (b) The third harmonic s-SNOM amplitude. The inset is a zoomed   view of the area sketched by the dashed rectangle. (c) Sectional profiles of   the topography and amplitude images. The two profiles are taken from the same   position as guided by the dashed line in topography.

摘要：以納米分辨率探測被膜材料覆蓋的結構有著很高的重要性。在本研究中，作者用散射型掃描近場光學顯微鏡（s-SNOM）探索了影響面下材料對比度和結構可見度的因素。作者生成了種包含不同掩埋結構的多層結構參考樣品，用來做s-SNOM成像。還研究了近場光學對比度對結構幾何形狀、尺寸和覆蓋層厚度的影響。結果表明區分掩埋狹縫圖樣比具有相同臨界尺寸的圓孔更容易。s-SNOM能夠在100多納米厚的聚甲基丙烯酸甲酯層下感知材料之間的差異，其面下空間分辨率可以好過100納米。

17.  華中科技大學 Dong Wei等人

Optical modulator based on the coupling effect of different surface plasmon modes excited on the metasurface. Opt. Mater. Expr..

Figure 6. SEM, AFM and near-field lightwave intensity distribution   of the NRANC metasurface. (a) SEM images of a metasurface sample, (b)   near-field lightwave intensity distribution on the sample, (c) near-field   lightwave intensity distribution along red dashed line. The white dashed   lines are the outlines of the nano-apertures. The red dotted line is the   trendline of the electric intensity distribution curve. (d) AFM image of the   metasurface sample.

摘要：作者設計并生成了種由帶中央納米柱的納米脊孔陣列(NRANC)構成的超表面光學調制器。研究者還細致地研究了，分布在納米脊孔的每個納米頂點和中央納米圓柱外緣上的局域表面等離子體（LSPs），與在周期性超表面上生成的表面等離子體激元(SPPs)，這二者之間的耦合效應。這種錐形結構可用于入射能量的集中與局部光場的增強。而在其上的感應電偶子則可以調節反射或透射性。這種在NRANC 上形成的LSPs的耦合效應將增強表面感應電偶子，并進步調節NRANC的光學性。通過改變超表面的幾何參數，可以調整LSPs模式的諧振頻率，并觀察到透射峰的平移，以及讓增強因數達到1.4×103。另方面，LSPs和SPPs之間的耦合則會激發法諾共振。在可見光和紅外范圍內調整照射激光的入射角則能調節SPPs的激發，并因此引起相對較大的透射光譜變化。于是通過進行近場光學測量，可以觀察到包括表面感應電荷信息在內的近場光學性，以及在45°入射的633納米TM激光照射下的個小（x方向上，約96納米）且亮的熱點。綜上，作者研究中構建的NRANC超表面突出了其在類似彩色濾光片、反射鏡、表面增強拉曼等方面的潛在應用前景。

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