We report the design of a mass spectrometer featuring an ion source that delivers ions directly into high vacuum from liquid inside a capillary with a sub-micrometer-diameter tip. The surface tension of water and formamide is sufficient to maintain a stable interface with high vacuum at the tip, and the gas load from the interface is negligible, even during electrospray. These conditions lifted the usual requirement of a differentially pumped system. The absence of a background gas also opened up the possibility of designing ion optics to collect and focus ions in order to achieve high overall transmission and detection efficiencies. We describe the operation and performance of the instrument and present mass spectra from solutions of salt ions and DNA bases in formamide and salt ions in water. The spectra show singly charged solute ions clustered with a small number of solvent molecules.

1.
3.
J. V.
Iribarne
and
B. A.
Thomson
,
J. Chem. Phys.
64
,
2287
(
1976
).
4.
M.
Gamero-Castaño
and
J.
Fernandez de la Mora
,
J. Chem. Phys.
113
,
815
(
2000
).
5.
M.
Dole
,
J. Chem. Phys.
49
,
2240
(
1968
).
7.
P.
Kebarle
and
U. H.
Verkerk
,
Mass Spectrom. Rev.
28
,
898
(
2009
).
8.
J.
Fernandez de la Mora
,
Anal. Chim. Acta
406
,
93
(
2000
).
9.
W.
Maulbetsch
,
B.
Wiener
,
W.
Poole
,
J.
Bush
, and
D.
Stein
,
Phys. Rev. Appl.
6
,
054006
(
2016
).
10.
D. S.
Swatik
and
C.
Hendricks
,
AIAA J.
6
,
1596
(
1968
).
11.
C.
Hendricks
and
D.
Swatik
,
Astronaut. Acta
18
,
295
(
1973
).
12.
P.
Prewett
and
D.
Jefferies
,
J. Phys. D: Appl. Phys.
13
,
1747
(
1980
).
13.
G.
Mair
and
R.
Forbes
,
J. Phys. D: Appl. Phys.
24
,
2217
(
1991
).
14.
B. P.
Stimpson
and
C. A.
Evans
,
Biol. Mass Spectrom.
5
,
52
(
1978
).
15.
B. P.
Stimpson
and
C. A.
Evans
,
J. Electrost.
5
,
411
(
1978
).
16.
C.
Perez-Martinez
and
P.
Lozano
,
Appl. Phys. Lett.
107
,
043501
(
2015
).
17.
K. D.
Cook
,
Mass Spectrom. Rev.
5
,
467
(
1986
).
18.
N.
Zolotoi
,
G.
Karpov
,
V.
Tal’roze
 et al,
Zh. Anal. Khim.
35
,
1781
(
1980
).
19.
N.
Zolotoi
,
G.
Karpov
, and
V.
Skurat
,
Theor. Exp. Chem.
24
,
235
(
1988
).
20.
M.
Wilm
and
M.
Mann
,
Anal. Chem.
68
,
1
(
1996
).
21.
R.
Juraschek
,
T.
Dulcks
, and
M.
Karas
,
J. Am. Soc. Mass Spectrom.
10
,
300
(
1999
).
22.
A.
El-Faramawy
,
K. W. M.
Siu
, and
B. A.
Thomson
,
J. Am. Soc. Mass Spectrom.
16
,
1702
(
2005
).
23.
M. E.
Belov
,
M. V.
Gorshkov
,
H. R.
Udseth
,
G. A.
Anderson
, and
R. D.
Smith
,
Anal. Chem.
72
,
2271
(
2000
).
24.
D.
Gao
,
H.
Liu
,
Y.
Jiang
, and
J.-M.
Lin
,
Lab Chip
13
,
3309
(
2013
).
25.
X.
Feng
,
B.-F.
Liu
,
J.
Li
, and
X.
Liu
,
Mass Spectrom. Rev.
34
,
535
(
2015
).
26.
A.
Oedit
,
P.
Vulto
,
R.
Ramautar
,
P. W.
Lindenburg
, and
T.
Hankemeier
,
Curr. Opin. Biotechnol.
31
,
79
(
2015
).
27.
B.
Wolf
,
Handbook of Ion Sources
(
CRC Press
,
1995
).
28.
R. D.
Bulushev
,
L. J.
Steinbock
,
S.
Khlybov
,
J. F.
Steinbock
,
U. F.
Keyser
, and
A.
Radenovic
,
Nano Lett.
14
,
6606
(
2014
).
29.
A.
Storm
,
J.
Chen
,
X.
Ling
,
H.
Zandbergen
, and
C.
Dekker
,
Nat. Mater.
2
,
537
(
2003
).
30.
P. E.
Miller
and
M. B.
Denton
,
J. Chem. Educ.
63
,
617
(
1986
).
31.
J. F.
De La Mora
and
I. G.
Loscertales
,
J. Fluid Mech.
260
,
155
(
2006
).
32.
Y.-H.
Chiu
,
B. L.
Austin
,
R. A.
Dressler
,
D.
Levandier
,
P. T.
Murray
,
P.
Lozano
, and
M.
Martinez-Sanchez
,
J. Propul. Power
21
,
416
(
2005
).
33.
W.
Luedtke
,
U.
Landman
,
Y.-H.
Chiu
,
D.
Levandier
,
R.
Dressler
,
S.
Sok
, and
M. S.
Gordon
,
J. Phys. Chem. A
112
,
9628
(
2008
).
34.
R.
Alonso-Matilla
,
J.
Fernández-García
,
H.
Congdon
, and
J.
Fernández de la Mora
,
J. Appl. Phys.
116
,
224504
(
2014
).
35.
I.
Guerrero
,
R.
Bocanegra
,
F.
Higuera
, and
J. F.
De La Mora
,
J. Fluid Mech.
591
,
437
(
2007
).
36.
R. E.
Pedder
, Extrel Application Note RA_2011A,
1
(
2002
).
37.
P.
Marriott
,
J. Phys. D: Appl. Phys.
19
,
L115
(
1986
).
38.
I.
Romero-Sanz
,
R.
Bocanegra
,
J.
Fernandez de la Mora
, and
M.
Gamero-Castaño
,
J. Appl. Phys.
94
,
3599
(
2003
).
39.
R. E.
Pedder
,
R. A.
Schaeffer
, E.C.M. SLP, and
E.
Drive
, Extrel Application Note RA_2003B, 1 (
1996
).
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