Development of Accelerator Based IR Light Sources and it's Applications

Refereed Papers related to Development of Accelerator Based IR Light Sources and it's Applications

1. Resonant Phonon-Induced Magnetic Domain Dynamics as Neel Temperature is Approaching in Nickel Oxide
   J.Y.H Bo, H. Zen, and H. Ohgaki, Japanese Journal of Applied Physics, accepted.

2. Bacterial Biomineralization: A Review and X-ray Diffraction Determination Table for Bacterial Biominerals
   T. Kono, T. Sakae, O. Tsuzukibashi, H. Zen, T. Sakai, Y. Takahashi, M. Saito, N. Shinozaki-Kuwahara, H. Nakada, K. Sato, A. Watanabe, T. Kuwada-Kusunose, K. Suzuki, T. Kaneda, Y. Hayakawa, H. Ohgaki, H. Okada, Journal of Hard Tissue Biology, 34, pp.181-198 (2025).

3. Observation of strong multi-pulse effects on spectral broadening of long-wavelength infrared pulses with 29.75 MHz repetition rate in a KRS-5 plate

H. Zen, Japanese Journal of Applied Physics, 64, 102001 (2025).

4. Infrared FEL-Induced Alteration of Zeta Potential in Electrochemically Grown Quantum Dots: Insights into Ion Modification
   S. Sucharitakul, S. Thanasanvorakun, V. Yarangsi, S. Yarin, K. Hongsith, M. Jitvisate, H. Ohgaki, S. Phadungdhitidhada, H. Zen, S. Rimjaem and S. Choopun, Nanomaterials 15, 1543 (2025).

5. Development of Array-type Secondary Electron Emission Monitor toward Single-shot Measurement of Extraction Efficiency of FEL Oscillators
   Z. Bi, K. Tanaka, H. Zen, H. Ohgaki, Particles 8, 81 (2025).

6. Electroretinograms of Cricket Compound Eyes Evoked by Ultraviolet, Visible, and Mid-infrared Irradiation
   F. Shishikura, K. Hayakawa, K. Nogami, T. Sakai, Y. Komatsuzaki, Y. Hayakawa, Y. Takahashi, T. Tanaka, H. Zen, T. Kii, and H. Ohgaki, Journal of Nihon University Medical Association 84, pp.163-170 (2025).

7. Structural Analysis of Carbohydrate Polymers by using Infrared Free Electron Laser
   T. Kawasaki, H. Zen, K. Nogami, K. Hayakawa, T. Sakai, Y. Hayakawa, Polymers 17, 2273 (2025).

8. Infrared Free-Electron Laser: A Versatile Molecular Cutter for Analyzing Solid-state Biomacromolecules
   T. Kawasaki, A. Nagase, K. Hayakawa, F. Teshima, K. Tanaka, H. Zen, F. Shishikura, N. Sei, T. Sakai, and Y. Hayakawa, ACS Omega, https://doi.org/10.1021/acsomega.4c07531 (2025).

9. Relationship between Ce3+ 5d1 level, conduction-band bottom, and shallow electron trap level in Gd3Ga5O12:Ce and Gd3Al1Ga4O12:Ce crystals studied via pump-probe absorption spectroscopy
   M. Kitaura, H. Zen, S. Watanabe, H. Masai, K. Kamada, K.J. Kim, A. Yoshikawa, J. Ueda, Optical Materials: X 25, 100398 (2025).

10. A van der Waals porous crystal featuring conformational flexibility and permanent porosity for ultrafast water release
    K. Maejima, H. Zen, H. Sato, E. Nishibori, T. Enjou, Y. Takeda, S. Minakata, E. Hisamura, K. Albrecht, Y. Ikemoto, I. Badia-Dominguez, J. Sanchez-Rincon, M. C. R. Delgado, Y. Yamamoto, and H. Yamagishi, Communications Chemistry 7, 282 (2024).

11. Temporal evolution of electron-bunch length in macropulse of resonator-type free-electron lasers
    N. Sei, H. Zen, H. Ohgaki and R. Hajima, iScience 27, 111402 (2024).

12. Measurement of temporal evolution of antiferromagnetic domain change in nickel oxide driven by 2TO phonon mode excitation via pump-probe experiment
    J.Y.H. Bo, H. Zen, H. Ohgaki, Japanease Journal of Applied Physics, 63, 112001 (2024).

13. Observation of selective excitation of Raman inactive phonon mode of strontium titanate through anti-Stokes hyper-Raman scattering process
    J.Y.H. Bo, H. Zen, K. Yoshida, K. Hachiya, R. Akasegawa, and H. Ohgaki, Journal of Infrared, Millimeter, and Terahertz Waves (2024), https://doi.org/10.1007/s10762-024-01014-8

14. Investigating structural property of human hair by using infrared free electron lasers

T. Kawasaki, A. Nagase, K. Hayakawa, F. Teshima, K. Tanaka, H. Zen, A. Irizawa, T. Sakai, and Y. Hayakawa, Discover Applied Sciences, 6, 397 (2024).

15. Beam characterization of mid-infrared free electron laser to drive high-harmonic generation

K. Kawase, H. Zen, T. Sakai, Y. Hayakawa, H. Ohgaki, and R. Hajima, Japanese Journal of Applied Physics, 63, 072001 (2024).

16. Breakdown of argon by a train of high-repetition long-wave-infrared pulses from a free-electron laser oscillator

R. Hajima, K. Kawase, J.K. Koga, H. Zen, and H. Ohgaki, Optics Express, 32, pp. 22722-22737 (2024).

17. Infrared free electron laser-irradiated polyleucine does not exert aggregates-induced aversive effects on mouse brain
    A. Mori, T. Shiroishi, J. Fujioka, T. Nakajima, S. Mitsui, H. Suginoma, Y. Kakuta, H. Zen, and K. Nakamura, Brain Disorders, 14, 100137 (2024).

18. Carrier-envelope phase stabilization in FEL oscillators
    R. Hajima, K. Kawase, H. Zen, and H. Ohgaki, Journal of Physics: Conference Series, 2687, 032013 (2024).

19. Nonlinear compression of naturally down-chirped superradiance pulses from a free-electron laser oscillator by thick germanium plates
    H. Zen, R. Hajima, and H. Ohgaki, Optics Express, 31, pp.40928-40936 (2023).

20. Dissosication process of polyalanine aggregates by free electron laser irradiation
    H. Okumura, S. G. Itoh, H. Zen, and K. Nakamura, PLOS ONE, 18(9): e0291093 (2023).

21. The Particle-Tracking Simulation of a New Photocathode RF Gun in the Free-Electron Laser Facility, KU-FEL
    Y. Zhao, H. Zen, and H. Ohgaki, Particles, 6, 638-646 (2023).

22. Formation of periodic surface structures on semiconductors under mid-infrared free-electron laser irradiation
    S. Masuno, M. Hashida, and H. Zen, IEEJ Transactions on Fundamentals and Materials, 143, pp.320-324 (2023).

23. Full characterization of superradiant pulses from a free-electron laser oscillator
    H. Zen, R. Hajima, and H. Ohgaki, Scientific Reports, 13, 6350 (2023).

24. Deformation of an electronic bunch caused by free-electron lasers
    N. Sei, H. Zen, and H. Ohgaki, Physica Scripta, 98, 025510 (2023).

25. Electroretinograms from Crayfish Compound Eyes Evoked by Mid-Infrared Irradiation: Spectral Sensitivity Measurements of the Fast and Late Reactions

   F. Shishikura, H. Zen, K. Hayakawa, Y. Komatsuzaki, Y. Hayakawa, T. Sakai, K. Nogami, Y. Takahashi, T. Tanaka,  T. Kii, and H. Ohgaki, Journal of Nihon University Medical Association, 82, pp.35-42 (2023).

26. Crystallinity in periodic nanostructure surface on Si substrates induced by near- and mid-infrared femtosecond laser irradiation
         R. Miyagawa, D. Kamibayashi, H. Nakamura, M. Hashida, H. Zen, T. Somekawa, T. Matsuoka, H. Ogura, D. Sagae, Y. Seto, T. Shobu, A. Tominaga, O. Eryu and N. Ozaki, Scientific Reports 12, 20955 (2022).

27. Degradation of Lignin by Infrared Free Electron Laser
          T. Kawasaki, H. Zen, T. Sakai, Y. Sumitomo, K. Nogami, K. Hayakawa, T. Yaji, T. Ohta, T. Nagata, Y. Hayakawa, Polymers, 14, 2401 (2022).

28. Enhancement of Oxidation of Silicon Carbide Originating from Stacking Faults Formed by Mode-Selective Phonon Excitation Using a Mid-Infrared Free Electron Laser
          Y. Maeda, H. Zen, A. Kitada, K. Murase, and K. Fukami, Journal of Physical Chemistry Letters, 13, 2956-2962 (2022).

29. Peak Shift of Coherent Edge Radiation Spectrum Depending on Radio-Frequency Field Phase of Accelerator
          N. Sei, H. Zen, and H. Ohgaki, Applied Sciences, 12, 626 (2022).

30. Study of the origin of the complex beam profile of a hole-coupled free electron laser oscillator
          H. Zen and H. Ohgaki, Journal of Optical Society of America A, 38, pp.1656-1661 (2021).

31. Mode-selective excitation of an infrared-inactive phonon mode in diamond using mid-infrared free electron laser
    R. Akasegawa, H. Zen, K. Hachiya, K. Yoshida, T. Goto, T. Sagawa, and H. Ohgaki, Japanese Journal of Applied Physics, 60, 102001 (2021). 

32. Application of mid-infrared free electron laser for structural analysis of biological materials
    T. Kawasaki, H. Zen, K. Ozaki, H. Yamada, K. Wakamatsu and S. Ito,
    Journal of Synchrotron Radiation, 28, https://doi.org/10.1107/S160057752001406X (2021).

33. Record high extraction efficiency of free electron laser oscillator
    H. Zen, H. Ohgaki, and R. Hajima, Applied Physics Express, 13, 102007 (2020).

34. High-extraction-efficiency operation of a midinfrared free electron laser enabled by dynamic cavity desynchronization
    H. Zen, H. Ohgaki, and R. Hajima, Physical Review Accelerators and Beams, 23, 070701 (2020).

35. Cellulose Degradation by Infrared Free Electron Laser
    T. Kawasaki, T. Sakai, H. Zen, Y. Sumitomo, K. Nogami, K. Hayakawa, T. Yaji, T. Ohta, K. Tsukiyama, and Y. Hayakawa,
    Energy & Fuels 34, pp.9064-9068 (2020).

36. Demonstration of Variable Polarized Coherent Terahertz Source
    S. Kashiwagi, H. Saito, F. Hinode, Y. Ishizuki, K. Kanomata, S. Miura, N. Morita, T. Muto, I. Nagasawa, K. Nanbu, K. Shibata, K. Takahashi,
    K. Terada, H. Yamada, H. Hama, H. Zen, and A. Irizawa, Infrared Physics & Technology, 106, 103274 (2020).

37. HgCdTe Detector Saturation Using Infrared Free Electron Laser and Infrared Synchrotron Radiation
    Y. Ikemoto and H. Zen, Infrared Physics & Technology 106 103268 (2020).

38. Two-photon Selective Excitation of Phonon-mode in Diamond Using Mid-Infrared Free-Electron Laser
    O. Sato, K. Yoshida, H. Zen, K. Hachiya, T. Goto, T. Sagawa and H. Ohgaki, Physics Letters A 384, 126223 (2020).

39. Research of Coherent Edge Radiation Generated by Electron Beams Oscillating Free-Electron Lasers
    N. Sei, H. Ogawa, T. Tanaka, Y. Hayakawa, T. Sakai, Y. Sumitomo, Y. Takahashi, K. Hayakawa, K. Nogami, H. Zen and H. Ohgaki,
    Journal of Physics: Conference Series, 1350, 012039 (2019).

40. Properties of THz Coherent Undulator Radiation Generated from a Compact Accelerator Source at Kyoto University
    S. Krainara, H. Zen, S. Chatani, T. Kii and H. Ohgaki, Review of Scientific Instruments 90, 103307 (2019).

41. Study on a long-life photocathode with an CsBr protective layer for an rf electron gun
    H. Ono, J. Miyamatsu, T. Tamba, K. Sakaue, M. Washio, H. Iijima, and H. Zen, Japanese Journal of Applied Physics, 58, 066005 (2019).

42. Investigation of Bunch Compressor and Compressed Electron Beam Characteristics by Coherent Transition Radiation
    S. Suphakul, H. Zen, T. Kii, H. Ohgaki, Particles, 2, Pages 32-43 (2019).

43. Study on Anomalous Photoemission of LaB6 at high temperatures
    K. Torgasin, K. Morita, H. Zen, K. Masuda, M. Bakr, K. Nagasaki, T. Kii, H. Ohgaki, Physica Scripta, 94 075701 (2019).

44. Photo‐Modification of Melanin by a Mid‐Infrared Free‐Electron Laser
    T. Kawasaki, A. Sato, Y. Tominaga, Y. Suzuki, T. Oyama, M. Tadokoro, K. Tsukiyama, K. Nokihara, H. Zen,
    Photochemistry and Photobiology, 95, Pages 946-950 (2019).

45. Measurement of Bunch Length Evolution in Electron Beam Macro-pulse of S-band Linac Using Coherent Edge Radiation
    N. Sei, H. Zen, H. Ohgaki, Physics Letters A, Volume 383, Pages 389-395 (2019).

46. Manipulation of Laser Distribution to Mitigate the Space-Charge Effect for Improving the Performance of a THz Coherent Undulator Radiation Source
    S. Krainara, S. Chatani, H. Zen, T. Kii, H. Ohgaki, Particles, Volume 1, Pages 238-252 (2018).

47. Study of the Saturation of Radiation Energy Caused by the Space Charge Effect in a Compact THz Coherent Radiation Source
    S. Krainara, S. Chatani, H. Zen, T. Kii, H. Ohgaki, Journal of Physics: Conference Series 1067, 032022 (2018)

48. Real-time Observation of Structural Change in Semi-crystalline Polymer Films through Mid-IR Transmission Spectroscopy: Determination of Instantaneous Film Temperature during Recrystallization
    S. K. Maurya, T. Nakajima, K. Mizobata, H. Zen, T. Kii, and H. Ohgaki, Optics Express, Volume 26, 21615 (2018).

49. Mid-­Infrared Free­ Electron Laser­ Evoked Discharge of Crayfish Compound Eyes
    F. Shishikura, H. Zen, K. Hayakawa, Y. Komatsuzaki, Y. Hayakawa, T. Sakai, T. Kii, H. Ohgaki,
    Journal of Nihon University Medical Association, Volume 77, Pages 159-164 (2018).

50. Visualizing Hidden Electron Trap Levels in Gd3Al2Ga3O12:Ce Crystals Using a Mid-Infrared Free Electron Laser
    M. Kitaura, H. Zen, K. Kamada, S. Kurosawa, S. Watanabe, A. Ohnishi, K. Hara, Applied Physics Letters, 112, 031112 (2018).

51. Measurement of Coherent Undulator Radiation of Compact Terahertz Radiation Source at Kyoto University
    S. Suphakul, H. Zen, T. Kii, H. Ohgaki, International Journal of Magnetics and Electromagnetism, 3, IJME-3-008 (2017).

52. Properties of quarter-wavelength coaxial cavity for triode-type thermionic RF gun
    K. Torgasin, K. Mishima, H. Zen, K. Yoshida, H. Negm, M. Omer, T. Kii, K. Nagasaki, K. Masuda, H. Ohgaki,
    Japanese Journal of Applied Physics 56, 096701 (2017).

53. Thermally Assisted Photoemission Effect on CeB6 and LaB6 for Application as Photocathodes
    K. Torgasin, K. Morita, H. Zen, K. Masuda, T. Katsurayama, T. Murata, S. Suphakul, H. Yamashita, T. Nogi, T. Kii, K. Nagasaki and H. Ohgaki
    Physical Review Accelerators and Beams 20, 073401 (2017).

54. Mode-Selective Phonon Excitation in Gallium Nitride Using Mid-Infrared Free-Electron Laser
    M. Kagaya, K. Yoshida, H. Zen, K. Hachiya, T. Sagawa, H. Ohgaki, Japanese Journal of Applied Physics,  Volume 56,  022701 (2017).

55. Present Status and Perspectives of Long Wavelength Free Electron Lasers at Kyoto University
    H. Zen, S. Suphakul, T. Kii, K. Masuda, H. Ohgaki, Physics Procedia, Volume 84, Pages 47-53 (2016).

56. Development of intense terahertz coherent synchrotron radiation at KU-FEL
    N. Sei, H. Zen, H. Ohgaki, Nuclear Instruments and Methods in Physics Research Section A, Volume 832, Pages 208-213 (2016).

57. Beam Dynamics Investigation for the Compact Seeded THz-FEL Amplifier
    S. Suphakul, K. Damminsek, H. Zen, T. Kii, H. Ohgaki, Energy Procedia, Volume 89,  Pages 373–381 (2016).

58. Time-resolved detection of structural change in polyethylene films using mid-infrared laser pulses
    E. Ageev, K. Mizobata, T. Nakajima, H. Zen, T. Kii and H. Ohgaki, Applied Physics Letters, Volume 107, 041904 (2015).

59. Emission properties and back-bombardment for CeB6 compared to LaB6
    M. Bakr, M. Kawai, T. Kii, H. Zen, K. Masuda, H. Ohgaki, Journal of Applied Physics, Volume 117, 064503 (2015).

60. Characterization of non-Gaussian mid-infrared free-electron laser beams by the knife-edge method
    Y. Qin, T. Nakajima, H. Zen, X. Wang, T. Kii, H. Ohgaki, Infrared Physics & Technology, Volume 66, Pages 146–151 (2014).

61. Damage threshold and focusability of mid-infrared free-electron laser pulses gated by a plasma mirror with nanosecond switching pulses
    X. Wang, T. Nakajima, H. Zen, T. Kii and H. Ohgaki, Applied Physics Letters 103, 191105 (2013).

62. Experimental demonstration of mode-selective phonon excitation of 6H-SiC by a mid-infrared laser with anti-Stokes Raman scattering spectroscopy
    K. Yoshida, T. Sonobe, H. Zen, K. Hachiya, K. Okumura, K. Mishima, M. Inukai, H. Negm, K. Torgasin, M. Omer, T. Kii, K. Masuda and H. Ohgaki
    Applied Physics Letters 103, 182103 (2013).

63. Pulse duration and wavelength stability measurements of a midinfrared free-electron laser
    Y. Qin, H. Zen, X. Wang, T. Kii, T. Nakajima, H. Ohgaki, Optics Letters, Vol. 38, Pages 1068-1070 (2013).

64. Optimization of the New Designed FEL Beam Transport Line
    K. Yoshida, H. Zen, K. Okumura, K. Shimahashi, M. Shibata, T. Komai, H. Imon, H. Negm, M. Omer, Y.W. Choi, R. Kinjo, T. Kii, K. Masuda, H. Ohgaki
    Zero-Carbon Energy Kyoto 2012, Pages 205-216 (2013).

65. Single-shot spectra of temporally selected micropulses from a mid-infrared free electron laser by upconversion
    X. Wang, T. Nakajima, H. Zen, T. Kii, H. Ohgaki, Optics Letters, Vol. 37, Pages 5148-5150 (2012).

66. Comparison of the Heating Properties of LaB6 and CeB6 Due to the Back Bombardment Effect in a Thermionic RF Gun
    M. A. Bakr,. R. Kinjo, Y. W. Choi, M. Omer, K. Yoshida, S. Ueda, M. Takasaki, K. Ishida, N. Kimura, H. Zen, T. Sonobe, T. Kii, K. Masuda and H. Ohgaki,
    Journal of the Korean Physical Society, Vol. 59, No. 5, Pages 3273-3279 (2011).

67. Back bombardment for dispenser and lanthanum hexaboride cathodes
    M. A. Bakr, R. Kinjo, Y.W. Choi, M. Omer, K. Yoshida, S. Ueda, M. Takasaki, K. Ishida, N. Kimura, T. Sonobe, T. Kii, K. Masuda, H. Ohgaki, H. Zen,
    Physical Review Special Topics - Accelerators and Beams 14, 060708 (2011).

68. FEL beamline for wide tunable range and beam sharing system at Kyoto University
    M. A. Bakr, K. Yoshida, K. Higashimura, S. Ueda, R. Kinjo, H. Zen, T. Sonobe, T. Kii, K. Masuda, H. Ohgaki
    AIP Conference Proceedings, Volume 1214, Pages 45-47 (2010).

69. Beam Energy Compensation in a Thermionic RF Gun by Cavity Detuning
    H. Zen, T. Kii,K. Masuda, R. Kinjo, K. Higashimura,K. Nagasaki, H. Ohgaki, IEEE transaction on nuclear science, Vol. 56, No. 3, Pages 1487-1491 (2009). 

70. Shielding analysis for a 40-MeV electron linac facility
    K. Masuda, T. Kii, H. Ohgaki, H. Zen, T. Yamazaki, Nuclear Technology, Volume 168, Issue 2, Pages 467-471 (2009). 

71. Lasing at 12um Mid Infrared Free Electron Laser in Kyoto University
    H. Ohgaki,T. Kii, K. Masuda, H. Zen, S. Sasaki, T. Shiiyama, R. Kinjo, K. Yoshikawa, T. Yamazaki
    Japanese Journal of Applied Physics, Vol.47, No.10, Pages 8091-8094 (2008). 

72. Development of IR-FEL Facility for Energy Science in Kyoto University
    H. Zen, T. Kii, K. Masuda, H. Ohgaki and T. Yamazaki, Infrared Physics and Technology, Volume 51, Issue 5, Pages 382-385 (2008). 

73. Reducing energy degradation due to back-bombardment effect with modulated rf input in S-band thermionic rf gun
    T. Kii, Y. Nakai, T. Fukui, H. Zen, K. Kusukame, N. Okawachi, M. Nakano, K. Masuda, H. Ohgaki, K. Yoshikawa, T. Yamazaki,
    AIP, Synchrotron Radiation Instrumentation, Pages 248-251 (2006).