Confocal Raman Imaging with WITec Sensitivity - Resolution - Speed. Always - Provable - Routinely

Transcription

1 Confocal Raman Imaging with WITec Sensitivity - Resolution - Speed Always - Provable - Routinely WITec GmbH, Ulm, Germany, info@witec.de,

2 A modular microscope series An Example: FLIM optical profiling Raman-SEM

3 Diffraction Limit and Confocal Microscopy Detection Pinhole Detection Lens Point Light Source Dichroic beam splitter Conjugate planes Objective Focal plane λ=532nm, NA=0.9 ΔX l = 360nm, ΔX a = 920nm

4 Confocal Raman Microscopy: Confocal Microscope + Raman Spectrometer => Imaging with chemical sensitivity

5 Challenges of the Confocal Raman Imaging Y= 20µm X= 20µm The ideal pixel size for an XY scan λ=532nm, NA=0.9 ΔX l = 360nm, ΔX a = 920nm Scan size Number of pixels Integration time Imaging time 20µm x 20µm 150 x 150 = ms 23 s ΔX l 3 = 120nm 50 ms 18 min 1 s > 6 h

6 Challenges of the Confocal Raman Imaging Number of spectra 20 x 20 = 400 Number of spectra 100 x 100 = x 40 [µm 2 ]

7 Confocal Raman Imaging with WITec Sensitivity - Resolution - Speed Always - Provable - Routinely WITec GmbH, Ulm, Germany, info@witec.de,

8 multi-mode fiber UHTS 300 CCD laser single-mode fiber Raman edge filter dichroic beam-splitter Z-stage piezo scanner

9 WITec Raman Spectroscopy System» Lens-based excitation optimized Raman Spectrometer Transmission >60% Superior peak shape conservation» Back-illuminated CCD or EM-CCD detectors highest Quantum efficiency 3 rd order 4 th order UHTS 300 Ultrahigh-Throughput Raman Spectrometer Detecting the 4 th order of Silicon

10 Resolution in Optical Microscopy - XY 1 50 nm Confocal Raman Image of a Carbon Nanotube Scan Range: 1.85 x 0.83 μm 65 x 27 pixels 34 ms integration/pixel 532 nm frequency-doubled Nd:YAG laser Objective: 100 x NA 0.9 Pinhole size: 50 μm Copyright WITec GmbH

11 Resolution in Optical Microscopy - XZ Depth Profiling on a suspended Graphene multilayer Point distance 50 nm 2 s integration/pixel 532 nm frequency-doubled Nd:YAG laser Objective: 100 x NA 0.9 Pinhole size: 10 μm Copyright WITec GmbH

12 Sensitivity & Speed - EM CCD Sample: Toothpaste 760 µs / spectrum, 40,000 spectra 1 µm Raman. AFM. SNOM True Surface => 42 s / image Image acquisition real-time demo Copyright WITec GmbH

13 Data acquisition and analysis

14 True Surface Microscopy The solution for confocal Raman imaging of large and very rough samples

15 True Surface Microscopy The solution for confocal Raman imaging of large and very rough samples

16 True Surface Microscopy The solution for confocal Raman imaging of large and very rough samples

17 True Surface Microscopy The solution for confocal Raman imaging of large and very rough samples

18 True Surface Microscopy 3D Confocal Raman Imaging of Transparent and Opaques Samples Tablet True Surface True Surface Confocal Raman image Raman Spectra 300µm 0µm High resolution Raman imaging without loss of signal due to the sample roughness

19 RISE Microscopy: Correlative Raman Imaging and Scanning Electron Microscopy

20 typical setup for Raman/SEM e-beam off-axis parabolic mirror advantages: can be retro-fitted to several SEM s disadvantages: detection excitation only single spectra => no imaging!! resolution (claim: 2µm; reality: 4-5µm) optical beam not visible in SEM => adjustment necessary offset between e-beam and Raman spot unknown (thermal drift, charging) restricted e-beam image size white light image has bad quality (max. 25µm Ø) not confocal!

21 what about EDX (energy dispersive X-ray spectroscopy)? - very powerful technique - X-rays are generated by the e-beam - X-ray spectrum characteristic for atoms - resolution typ. 1-2 µm Problem: only atoms can be distinguished - no chemistry (e.g. polymers) PMMA: PS: 1-2 µm characteristic X-radiation

22 RISE: Correlative Raman Imaging and Scanning Electron Microscopy

23 RISE: Correlative Raman Imaging and Scanning Electron Microscopy

24 RISE: Correlative Raman Imaging and Scanning Electron Microscopy hamster brain (white and gray brain matter) gray white brain matter

25 RISE: Correlative Raman Imaging and Scanning Electron Microscopy carbon plagioclase (feldspar) apatite plagioclase (feldspar) Diorite

26 4 G FS V 20 1 RISE: Correlative Raman Imaging and Scanning Electron Microscopy graphene on Si

27 4 G FS V 20 1 RISE: Correlative Raman Imaging and Scanning Electron Microscopy graphene on Si

28 RISE: Correlative Raman Imaging and Scanning Electron Microscopy D blue, dark green: light green, red: yellow: G 1 layer >1 layer Si D

29 RISE: Correlative Raman Imaging and Scanning Electron Microscopy PS PMMA

30 Al, K Fe, Ca, K FS V O Na, K G Si SEM

31 A modular microscope series An Example: FLIM optical profiling Raman-SEM

32 High Resolution - High Sensitivity Fast Imaging 1 µm Raman. AFM. SNOM True Surface True Surface-Raman 3D-Raman Fast Imaging acquisition real-time AFM-Raman SEM-Raman Copyright WITec GmbH

33 MERCI