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Papadakis A, Gyenis A, Pothof J, H J Hoeijmakers J, Papantonis A, Beyer A. Age-associated transcriptional stress due to accelerated elongation and increased stalling of RNAPII. Nat Genet 2023; 55:2011-2012. [PMID: 38001379 DOI: 10.1038/s41588-023-01601-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2023]
Affiliation(s)
- Antonios Papadakis
- Cluster of Excellence on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Akos Gyenis
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
- University of Cologne, Faculty of Medicine, Cluster of Excellence on Cellular Stress Responses in Aging-associated Diseases (CECAD), Institute for Genome Stability in Ageing and Disease, Cologne, Germany
| | - Joris Pothof
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jan H J Hoeijmakers
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
- University of Cologne, Faculty of Medicine, Cluster of Excellence on Cellular Stress Responses in Aging-associated Diseases (CECAD), Institute for Genome Stability in Ageing and Disease, Cologne, Germany
- Princess Maxima Center for Pediatric Oncology, Oncode Institute, Utrecht, The Netherlands
| | - Argyris Papantonis
- Institute of Pathology, University Medical Centre Göttingen, Göttingen, Germany
| | - Andreas Beyer
- Cluster of Excellence on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
- Institute for Genetics, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany.
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Gyenis A, Chang J, Demmers JJPG, Bruens ST, Barnhoorn S, Brandt RMC, Baar MP, Raseta M, Derks KWJ, Hoeijmakers JHJ, Pothof J. Genome-wide RNA polymerase stalling shapes the transcriptome during aging. Nat Genet 2023; 55:268-279. [PMID: 36658433 PMCID: PMC9925383 DOI: 10.1038/s41588-022-01279-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 12/07/2022] [Indexed: 01/21/2023]
Abstract
Gene expression profiling has identified numerous processes altered in aging, but how these changes arise is largely unknown. Here we combined nascent RNA sequencing and RNA polymerase II chromatin immunoprecipitation followed by sequencing to elucidate the underlying mechanisms triggering gene expression changes in wild-type aged mice. We found that in 2-year-old liver, 40% of elongating RNA polymerases are stalled, lowering productive transcription and skewing transcriptional output in a gene-length-dependent fashion. We demonstrate that this transcriptional stress is caused by endogenous DNA damage and explains the majority of gene expression changes in aging in most mainly postmitotic organs, specifically affecting aging hallmark pathways such as nutrient sensing, autophagy, proteostasis, energy metabolism, immune function and cellular stress resilience. Age-related transcriptional stress is evolutionary conserved from nematodes to humans. Thus, accumulation of stochastic endogenous DNA damage during aging deteriorates basal transcription, which establishes the age-related transcriptome and causes dysfunction of key aging hallmark pathways, disclosing how DNA damage functionally underlies major aspects of normal aging.
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Affiliation(s)
- Akos Gyenis
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- University of Cologne, Faculty of Medicine, Cluster of Excellence for Aging Research, Institute for Genome Stability in Ageing and Disease, Cologne, Germany
| | - Jiang Chang
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Joris J P G Demmers
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Serena T Bruens
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Sander Barnhoorn
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Renata M C Brandt
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Marjolein P Baar
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marko Raseta
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Kasper W J Derks
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics and School for Oncology & Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jan H J Hoeijmakers
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- University of Cologne, Faculty of Medicine, Cluster of Excellence for Aging Research, Institute for Genome Stability in Ageing and Disease, Cologne, Germany
- Princess Maxima Center for Pediatric Oncology, Oncode Institute, Utrecht, The Netherlands
| | - Joris Pothof
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands.
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Kim DE, Dollé MET, Vermeij WP, Gyenis A, Vogel K, Hoeijmakers JHJ, Wiley CD, Davalos AR, Hasty P, Desprez P, Campisi J. Deficiency in the DNA repair protein ERCC1 triggers a link between senescence and apoptosis in human fibroblasts and mouse skin. Aging Cell 2020; 19:e13072. [PMID: 31737985 PMCID: PMC7059167 DOI: 10.1111/acel.13072] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 10/07/2019] [Accepted: 10/30/2019] [Indexed: 12/11/2022] Open
Abstract
ERCC1 (excision repair cross complementing‐group 1) is a mammalian endonuclease that incises the damaged strand of DNA during nucleotide excision repair and interstrand cross‐link repair. Ercc1−/Δ mice, carrying one null and one hypomorphic Ercc1 allele, have been widely used to study aging due to accelerated aging phenotypes in numerous organs and their shortened lifespan. Ercc1−/Δ mice display combined features of human progeroid and cancer‐prone syndromes. Although several studies report cellular senescence and apoptosis associated with the premature aging of Ercc1−/Δ mice, the link between these two processes and their physiological relevance in the phenotypes of Ercc1−/Δ mice are incompletely understood. Here, we show that ERCC1 depletion, both in cultured human fibroblasts and the skin of Ercc1−/Δ mice, initially induces cellular senescence and, importantly, increased expression of several SASP (senescence‐associated secretory phenotype) factors. Cellular senescence induced by ERCC1 deficiency was dependent on activity of the p53 tumor‐suppressor protein. In turn, TNFα secreted by senescent cells induced apoptosis, not only in neighboring ERCC1‐deficient nonsenescent cells, but also cell autonomously in the senescent cells themselves. In addition, expression of the stem cell markers p63 and Lgr6 was significantly decreased in Ercc1−/Δ mouse skin, where the apoptotic cells are localized, compared to age‐matched wild‐type skin, possibly due to the apoptosis of stem cells. These data suggest that ERCC1‐depleted cells become susceptible to apoptosis via TNFα secreted from neighboring senescent cells. We speculate that parts of the premature aging phenotypes and shortened health‐ or lifespan may be due to stem cell depletion through apoptosis promoted by senescent cells.
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Affiliation(s)
- Dong Eun Kim
- Buck Institute for Research on Aging Novato CA USA
| | - Martijn E. T. Dollé
- Centre for Health Protection Research National Institute of Public Health and the Environment (RIVM) Bilthoven The Netherlands
| | - Wilbert P. Vermeij
- Department of Molecular Genetics Erasmus University Medical Center Rotterdam The Netherlands
- Princess Máxima Center for Pediatric Oncology ONCODE Institute Utrecht The Netherlands
| | | | | | - Jan H. J. Hoeijmakers
- Department of Molecular Genetics Erasmus University Medical Center Rotterdam The Netherlands
- Princess Máxima Center for Pediatric Oncology ONCODE Institute Utrecht The Netherlands
- CECAD Forschungszentrum Köln Germany
| | | | | | - Paul Hasty
- Department of Molecular Medicine Sam and Ann Barshop Institute for Longevity and Aging Studies University of Texas Health Science Center San Antonio TX USA
| | | | - Judith Campisi
- Buck Institute for Research on Aging Novato CA USA
- Lawrence Berkeley National Laboratory Berkeley CA USA
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4
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Milanese C, Bombardieri CR, Sepe S, Barnhoorn S, Payán-Goméz C, Caruso D, Audano M, Pedretti S, Vermeij WP, Brandt RMC, Gyenis A, Wamelink MM, de Wit AS, Janssens RC, Leen R, van Kuilenburg ABP, Mitro N, Hoeijmakers JHJ, Mastroberardino PG. DNA damage and transcription stress cause ATP-mediated redesign of metabolism and potentiation of anti-oxidant buffering. Nat Commun 2019; 10:4887. [PMID: 31653834 PMCID: PMC6814737 DOI: 10.1038/s41467-019-12640-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 09/22/2019] [Indexed: 12/13/2022] Open
Abstract
Accumulation of DNA lesions causing transcription stress is associated with natural and accelerated aging and culminates with profound metabolic alterations. Our understanding of the mechanisms governing metabolic redesign upon genomic instability, however, is highly rudimentary. Using Ercc1-defective mice and Xpg knock-out mice, we demonstrate that combined defects in transcription-coupled DNA repair (TCR) and in nucleotide excision repair (NER) directly affect bioenergetics due to declined transcription, leading to increased ATP levels. This in turn inhibits glycolysis allosterically and favors glucose rerouting through the pentose phosphate shunt, eventually enhancing production of NADPH-reducing equivalents. In NER/TCR-defective mutants, augmented NADPH is not counterbalanced by increased production of pro-oxidants and thus pentose phosphate potentiation culminates in an over-reduced redox state. Skin fibroblasts from the TCR disease Cockayne syndrome confirm results in animal models. Overall, these findings unravel a mechanism connecting DNA damage and transcriptional stress to metabolic redesign and protective antioxidant defenses. ERCC1 is involved in a number of DNA repair pathways including nucleotide excision repair. Here the authors showed that reduced transcription in Ercc1-deficient mouse livers and cells increases ATP levels, suppressing glycolysis and rerouting glucose into the pentose phosphate shunt that generates reductive stress.
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Affiliation(s)
- Chiara Milanese
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Cíntia R Bombardieri
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Sara Sepe
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Sander Barnhoorn
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - César Payán-Goméz
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands.,Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Bogotá, Colombia
| | - Donatella Caruso
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Matteo Audano
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Silvia Pedretti
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Wilbert P Vermeij
- Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Renata M C Brandt
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Akos Gyenis
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands.,Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | - Mirjam M Wamelink
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, the Netherlands
| | - Annelieke S de Wit
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Roel C Janssens
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - René Leen
- Laboratory of Genetic Metabolic Diseases, Academic Medical Center, Amsterdam, the Netherlands
| | | | - Nico Mitro
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Jan H J Hoeijmakers
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands.,Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands.,Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany.,Oncode Institute, Princess Máxima Center, Utrecht, Netherlands
| | - Pier G Mastroberardino
- Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands. .,Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy.
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Hazard TM, Gyenis A, Di Paolo A, Asfaw AT, Lyon SA, Blais A, Houck AA. Nanowire Superinductance Fluxonium Qubit. Phys Rev Lett 2019; 122:010504. [PMID: 31012689 DOI: 10.1103/physrevlett.122.010504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 10/05/2018] [Indexed: 06/09/2023]
Abstract
We characterize a fluxonium qubit consisting of a Josephson junction inductively shunted with a NbTiN nanowire superinductance. We explain the measured energy spectrum by means of a multimode theory accounting for the distributed nature of the superinductance and the effect of the circuit nonlinearity to all orders in the Josephson potential. Using multiphoton Raman spectroscopy, we address multiple fluxonium transitions, observe multilevel Autler-Townes splitting and measure an excited state lifetime of T_{1}=20 μs. By measuring T_{1} at different magnetic flux values, we find a crossover in the lifetime limiting mechanism from capacitive to inductive losses.
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Affiliation(s)
- T M Hazard
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - A Gyenis
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - A Di Paolo
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - A T Asfaw
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - S A Lyon
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - A Blais
- Institut quantique and Département de Physique, Université de Sherbrooke, Sherbrooke J1K 2R1 Quebec, Canada
- Canadian Institute for Advanced Research, Toronto, M5G 1M1 Ontario, Canada
| | - A A Houck
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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6
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Bruens ST, Milanese C, Verkaik N, Mastroberardino P, Gyenis A, Chang J, Derks K, Wiemer E, van Gent D, van Weerden W, Jenster G, Hoeijmakers J, Pothof J. Abstract 1657: Mapping mechanisms of radiotherapy resistance in prostate cancer. Cancer Res 2016. [DOI: 10.1158/1538-7445.am2016-1657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Cancer cells that acquire radio-resistance are major problem for treatment outcome. We aimed at identifying mechanisms and networks that control ionizing radiation (IR)-resistance in prostate cancer cells. To this end, we applied to cancer cell lines an identical radiotherapy regiment as performed in the clinic, i.e. a total dose of 78 Gy in steps of 2 Gy per day for 5 consecutive days followed by 2 days rest. We observed that radio-resistance occurs early during treatment as seen in colony survival assays in which 100% of cells that can form colonies are resistant up to 8 Gy. Remarkably, a two-week period of culturing without radiotherapy completely sensitized these resistant cancer cell lines, indicating that resistance is not acquired by permanent mutations or chromosomal rearrangements. Currently, we are characterizing these extreme resistant cancer cell cultures by comparing these to their sensitive parental cancer cell lines and the two-week re-sensitized cancer cell lines. We observe changes in DNA repair pathway utilization, DNA damage checkpoint activation and energy metabolism parameters, but not in PI3-kinase signalling and cancer stem cell markers. We also performed genome-wide gene expression analysis by next generation sequencing and isolated gene signatures that correlate with resistance. Based on our results we applied inhibitors to sensitize these IR-resistant cells. Notably, application of single inhibitors did not lead to sensitivity. Combinations of small molecule inhibitors however, were able to sensitize these cancer cell lines, indicating that IR-resistance is a multi-factorial process. In summary, mapping gene networks and mechanisms will uncover new pathways associated with IR-resistance.
Citation Format: Serena T. Bruens, Chiara Milanese, Nicole Verkaik, Pier Mastroberardino, Akos Gyenis, Jiang Chang, Kasper Derks, Erik Wiemer, Dik van Gent, Wytske van Weerden, Guido Jenster, Jan Hoeijmakers, Joris Pothof. Mapping mechanisms of radiotherapy resistance in prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1657.
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Kushwaha SK, Pletikosić I, Liang T, Gyenis A, Lapidus SH, Tian Y, Zhao H, Burch KS, Lin J, Wang W, Ji H, Fedorov AV, Yazdani A, Ong NP, Valla T, Cava RJ. Sn-doped Bi1.1Sb0.9Te2S bulk crystal topological insulator with excellent properties. Nat Commun 2016; 7:11456. [PMID: 27118032 PMCID: PMC4853473 DOI: 10.1038/ncomms11456] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 03/30/2016] [Indexed: 12/03/2022] Open
Abstract
A long-standing issue in topological insulator research has been to find a bulk single crystal material that provides a high-quality platform for characterizing topological surface states without interference from bulk electronic states. This material would ideally be a bulk insulator, have a surface state Dirac point energy well isolated from the bulk valence and conduction bands, display quantum oscillations from the surface state electrons and be growable as large, high-quality bulk single crystals. Here we show that this material obstacle is overcome by bulk crystals of lightly Sn-doped Bi1.1Sb0.9Te2S grown by the vertical Bridgman method. We characterize Sn-BSTS via angle-resolved photoemission spectroscopy, scanning tunnelling microscopy, transport studies, X-ray diffraction and Raman scattering. We present this material as a high-quality topological insulator that can be reliably grown as bulk single crystals and thus studied by many researchers interested in topological surface states. An ideal topological insulator possesses an insulating bulk and a unique conducting surface however such behaviour is typically inhibited by bulk conduction due to defects. Here, the authors show that Sn-doped Bi1.1Sb0.9Te2S grown by the vertical Bridgman technique might overcome this hurdle.
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Affiliation(s)
- S K Kushwaha
- Frick Chemistry Laboratory, Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - I Pletikosić
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.,Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Upton, New York 11973, USA
| | - T Liang
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - A Gyenis
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - S H Lapidus
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yao Tian
- Department of Physics, University of Toronto, Toronto, Ontario, Canada M5S 1A7
| | - He Zhao
- Department of Physics, Boston College, Boston, Massachusetts 02467-3804, USA
| | - K S Burch
- Department of Physics, Boston College, Boston, Massachusetts 02467-3804, USA
| | - Jingjing Lin
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Wudi Wang
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Huiwen Ji
- Frick Chemistry Laboratory, Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - A V Fedorov
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Ali Yazdani
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - N P Ong
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - T Valla
- Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Upton, New York 11973, USA
| | - R J Cava
- Frick Chemistry Laboratory, Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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Misra S, Zhou BB, Drozdov IK, Seo J, Urban L, Gyenis A, Kingsley SCJ, Jones H, Yazdani A. Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields. Rev Sci Instrum 2013; 84:103903. [PMID: 24182125 DOI: 10.1063/1.4822271] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We describe the construction and performance of a scanning tunneling microscope capable of taking maps of the tunneling density of states with sub-atomic spatial resolution at dilution refrigerator temperatures and high (14 T) magnetic fields. The fully ultra-high vacuum system features visual access to a two-sample microscope stage at the end of a bottom-loading dilution refrigerator, which facilitates the transfer of in situ prepared tips and samples. The two-sample stage enables location of the best area of the sample under study and extends the experiment lifetime. The successful thermal anchoring of the microscope, described in detail, is confirmed through a base temperature reading of 20 mK, along with a measured electron temperature of 250 mK. Atomically resolved images, along with complementary vibration measurements, are presented to confirm the effectiveness of the vibration isolation scheme in this instrument. Finally, we demonstrate that the microscope is capable of the same level of performance as typical machines with more modest refrigeration by measuring spectroscopic maps at base temperature both at zero field and in an applied magnetic field.
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Affiliation(s)
- S Misra
- Department of Physics and Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544, USA
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